William Lafargue-Dit-Hauret
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Previous Organizations / Institutes
The organizations / institutes from the scholar's other articles in the past ten years
Research Subjects
William Lafargue-Dit-Hauret has a total of 139 co-authors. Here are the top co-authors by number of shared publications:
- Xavier Rocquefelte
Univ Rennes, CNRS, Institut des Sciences Chimiques de Rennes – UMR 6226, F-35000 Rennes, France
7 shared publications Xavier Rocquefelte
Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) UMR 6226, F-35000 Rennes, France
5 shared publications- Aldo Humberto Romero
West Virginia University
3 shared publications - Didier Bégué
Université de Pau et des Pays de l’Adour
3 shared publications - Andrej Zorko
Jozef Stefan Institute
2 shared publications - Andrew Ozarowski
National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
2 shared publications
Latest Publications
- 3 April 2026
- Published by Agence Bibliographique de l'Enseignement Supérieur
Modélisation des propriétés magnétiques et multiferroïques d'oxydes de cuivre
Les matériaux multiferroïques, dans lesquels magnétisme et ferroélectricité coexistent, sont un intérêt majeur dans le domaine du stockage de l'information. Un couplage magnétoélectrique robuste, ainsi qu'une polarisation électrique importante, sont les conditions requises à température ambiante pour ces matériaux multifonctionnels. Ce manuscrit rend compte de travaux théoriques visant à principalement caractériser les propriétés magnétiques d'oxydes à majorité cuivrés, susceptibles de répondre à ces exigences. Une première partie vise à une présentation succincte des cuprates, et de concepts fondamentaux concernant le magnétisme et la multiferroïcité. La seconde partie expose les méthodes de modélisation employées. Le chapitre trois donne à un aperçu de techniques expérimentales, tels que le magnétomètre à SQUID ou la RPE. Ensuite, les composés AFeO₃ (A = Sc, In et Bi) et un complexe à base de chrome servent de terrain de jeu, à la mise en place de l'approche calculatoire. La complémentarité entre les méthodes ab initio et les techniques de type Monte-Carlo ou Diagonalisation Exacte, permet une description complète du diagramme de phases magnétiques, alimentée d'une discussion permanente avec l'expérience. Une stratégie similaire est utilisée dans le chapitre suivant, avec l'étude du composé SeCuO₃ et de ses fluctuations quantiques. La dernière partie consiste en la caractérisation de l'effet d'une pression physique (hydrostatique ou uniaxiale) ou chimique sur les propriétés magnétiques des composés CuO, Cu₂OX₂ et CuX₂ (X=F, Cl, Br et I).
- 3 April 2026
- Published by Agence Bibliographique de l'Enseignement Supérieur
Modélisation des propriétés magnétiques et multiferroïques d'oxydes de cuivre
Les matériaux multiferroïques, dans lesquels magnétisme et ferroélectricité coexistent, sont un intérêt majeur dans le domaine du stockage de l'information. Un couplage magnétoélectrique robuste, ainsi qu'une polarisation électrique importante, sont les conditions requises à température ambiante pour ces matériaux multifonctionnels. Ce manuscrit rend compte de travaux théoriques visant à principalement caractériser les propriétés magnétiques d'oxydes à majorité cuivrés, susceptibles de répondre à ces exigences. Une première partie vise à une présentation succincte des cuprates, et de concepts fondamentaux concernant le magnétisme et la multiferroïcité. La seconde partie expose les méthodes de modélisation employées. Le chapitre trois donne à un aperçu de techniques expérimentales, tels que le magnétomètre à SQUID ou la RPE. Ensuite, les composés AFeO₃ (A = Sc, In et Bi) et un complexe à base de chrome servent de terrain de jeu, à la mise en place de l'approche calculatoire. La complémentarité entre les méthodes ab initio et les techniques de type Monte-Carlo ou Diagonalisation Exacte, permet une description complète du diagramme de phases magnétiques, alimentée d'une discussion permanente avec l'expérience. Une stratégie similaire est utilisée dans le chapitre suivant, avec l'étude du composé SeCuO₃ et de ses fluctuations quantiques. La dernière partie consiste en la caractérisation de l'effet d'une pression physique (hydrostatique ou uniaxiale) ou chimique sur les propriétés magnétiques des composés CuO, Cu₂OX₂ et CuX₂ (X=F, Cl, Br et I).
- Open Access
- 18 October 2024
- Published by Royal Society of Chemistry (RSC) in EES Catalysis
- Vol. 3 (2) , 286-296
Self-assembled infinite silver cluster with atomic precision as a scalable catalyst for CO 2 -electroreduction under industry-relevant reaction rates
Scalable infinite silver acetylide cluster as a CO 2 reduction catalyst with high selectivity for CO at industry-relevant rates.
- 18 October 2024
- Published by Royal Society of Chemistry (RSC) in EES Catalysis
- Vol. 3 (2) , 286-296
Open AccessSelf-assembled infinite silver cluster with atomic precision as a scalable catalyst for CO 2 -electroreduction under industry-relevant reaction rates
Scalable infinite silver acetylide cluster as a CO 2 reduction catalyst with high selectivity for CO at industry-relevant rates.
- 6 June 2024
- Published by Springer Nature in Journal of Materials Science
- Vol. 59 (24) , 10888-10903
A DFT bottom-up approach on non-fullerene acceptors: what makes highly efficient acceptors
- 6 June 2024
- Published by Springer Nature in Journal of Materials Science
- Vol. 59 (24) , 10888-10903
A DFT bottom-up approach on non-fullerene acceptors: what makes highly efficient acceptors
- 26 January 2024
- Published by American Physical Society (APS) in Physical Review B
- Vol. 109 (2) , 024113
Ferroelectricity and chirality in the crystalWe study from first-principles calculations the ferroelectric structural phase transition of crystal. The calculations of phonons and Born effective charges of the paraelectric phase allow us to identify a polar instability that is unstable in both transverse-optic and longitudinal-optic versions, giving rise to an entire branch of instability along a propagation vector parallel to the mode polarization (the hexagonal axe). This is the hint of hyperferroelectricity and the stable head-to-head and tail-to-tail domain, as recently reported from both experiments and theory. Then, our analysis of the ferroelectric phase shows that the polarization of is uniaxial along the hexagonal axes and with small in-plane components due to a piezoelectric effect. The symmetry-adapted mode analysis shows that the total ferroelectric ground-state distortion comes mainly from polar distortions of the unstable polar phonon mode but also from an invariant, cooperative mode that amplifies the polar deformation. We also build a phenomenological model that highlights how the coupling between these modes is at play and helps us understand how to reproduce the second-order phase transition. Lastly, we also quantify the structural chirality through the continuous symmetry measure method and trace its origin to the polar unstable mode itself. By extending our approach to the phonon states, we further show that the chirality is poorly affected by the relaxation but could also be enhanced by activating high-frequency modes with polar symmetry. Finally, we study the phonon angular momentum (AM) distribution in both phases and identify trends in the AM behavior across the Brillouin zone.- 26 January 2024
- Published by American Physical Society (APS) in Physical Review B
- Vol. 109 (2) , 024113
Ferroelectricity and chirality in the crystalWe study from first-principles calculations the ferroelectric structural phase transition of crystal. The calculations of phonons and Born effective charges of the paraelectric phase allow us to identify a polar instability that is unstable in both transverse-optic and longitudinal-optic versions, giving rise to an entire branch of instability along a propagation vector parallel to the mode polarization (the hexagonal axe). This is the hint of hyperferroelectricity and the stable head-to-head and tail-to-tail domain, as recently reported from both experiments and theory. Then, our analysis of the ferroelectric phase shows that the polarization of is uniaxial along the hexagonal axes and with small in-plane components due to a piezoelectric effect. The symmetry-adapted mode analysis shows that the total ferroelectric ground-state distortion comes mainly from polar distortions of the unstable polar phonon mode but also from an invariant, cooperative mode that amplifies the polar deformation. We also build a phenomenological model that highlights how the coupling between these modes is at play and helps us understand how to reproduce the second-order phase transition. Lastly, we also quantify the structural chirality through the continuous symmetry measure method and trace its origin to the polar unstable mode itself. By extending our approach to the phonon states, we further show that the chirality is poorly affected by the relaxation but could also be enhanced by activating high-frequency modes with polar symmetry. Finally, we study the phonon angular momentum (AM) distribution in both phases and identify trends in the AM behavior across the Brillouin zone.- 14 November 2023
- Published by American Physical Society (APS) in Physical Review B
- Vol. 108 (20) , L201112
Large and tunable spin-orbit effect of orbitals through structural cavities in crystalsWe explore from first-principles calculations the ferroelectric material as a model for controlling the spin-orbit interaction (SOC) in crystalline solids. The SOC has a surprisingly strong effect on the structural energy landscape by deepening the ferroelectric double well. We observe that this effect comes from a specific Pb Wyckoff site that lies on the verge of a natural cavity channel of the crystal. We also find that a unique cavity state is formed by the empty states of another Pb site at the edge of the cavity channel. This cavity state exhibits a sizable spin splitting with a mixed Rashba-Weyl character and a topologically protected crossing of the related bands. We also show that the ferroelectric properties and the significant SOC effects are exceptionally robust in the presence of n-type doping at levels of up to several electrons per unit cell. We trace the provenance of these original effects to the unique combination of the structural cavity channel and the chemistry of the Pb atoms with orbitals localizing inside the channel.- 14 November 2023
- Published by American Physical Society (APS) in Physical Review B
- Vol. 108 (20) , L201112
Large and tunable spin-orbit effect of orbitals through structural cavities in crystalsWe explore from first-principles calculations the ferroelectric material as a model for controlling the spin-orbit interaction (SOC) in crystalline solids. The SOC has a surprisingly strong effect on the structural energy landscape by deepening the ferroelectric double well. We observe that this effect comes from a specific Pb Wyckoff site that lies on the verge of a natural cavity channel of the crystal. We also find that a unique cavity state is formed by the empty states of another Pb site at the edge of the cavity channel. This cavity state exhibits a sizable spin splitting with a mixed Rashba-Weyl character and a topologically protected crossing of the related bands. We also show that the ferroelectric properties and the significant SOC effects are exceptionally robust in the presence of n-type doping at levels of up to several electrons per unit cell. We trace the provenance of these original effects to the unique combination of the structural cavity channel and the chemistry of the Pb atoms with orbitals localizing inside the channel.- 24 October 2023
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry A
- Vol. 127 (43) , 9088-9097
CHNO – Formylnitrene, Cyanic, Isocyanic, Fulminic, and Isofulminic Acids and their Interrelationships at DFT and CASPT2 Levels of Theory
Fulminic and cyanic acids played a decisive role in the conception of isomerism 200 years ago. Cyanic (HOCN), isocyanic (HNCO), and fulminic (HCNO) acids have been detected in several interstellar sources, but isofulminic acid (HONC) is little known. Here we examine the interrelationships between the four acids and formylnitrene, HC(O)N, at the CASPT2 and three DFT levels. Formylnitrene has a triplet ground state, T0, a closed shell singlet (CSS), S0, and an open-shell singlet (OSS), S1, lying ∼7 and 27 kcal/mol above T0, respectively. The CSS is weakly stabilized by a 12 kcal/mol bond between the N and the O atoms. A conical intersection 12 kcal/mol above T0 permits easy T0-S0 interchange. Formyl azide and formylnitrene (T0 and S0) are isomerized thermally to HNCO. HOCN is best obtained via dissociation of the nitrene (or of HNCO) to H• + NCO• radicals ∼46 kcal/mol above the T0 nitrene. Isofulminic acid, HONC, isomerizes readily to cyanic acid, HOCN, in thermal and photochemical reactions. Fulminic acid, HCNO, can isomerize to HNCO via CSS formylnitrene. Easy tautomerization prevents the preparation of HOCN in quantity. The barrier to isomerization is strongly reduced in small hydrogen-bonded aggregates so that trace amounts of HOCN can exist in equilibrium with HNCO.
- 24 October 2023
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry A
- Vol. 127 (43) , 9088-9097
CHNO – Formylnitrene, Cyanic, Isocyanic, Fulminic, and Isofulminic Acids and their Interrelationships at DFT and CASPT2 Levels of Theory
Fulminic and cyanic acids played a decisive role in the conception of isomerism 200 years ago. Cyanic (HOCN), isocyanic (HNCO), and fulminic (HCNO) acids have been detected in several interstellar sources, but isofulminic acid (HONC) is little known. Here we examine the interrelationships between the four acids and formylnitrene, HC(O)N, at the CASPT2 and three DFT levels. Formylnitrene has a triplet ground state, T0, a closed shell singlet (CSS), S0, and an open-shell singlet (OSS), S1, lying ∼7 and 27 kcal/mol above T0, respectively. The CSS is weakly stabilized by a 12 kcal/mol bond between the N and the O atoms. A conical intersection 12 kcal/mol above T0 permits easy T0-S0 interchange. Formyl azide and formylnitrene (T0 and S0) are isomerized thermally to HNCO. HOCN is best obtained via dissociation of the nitrene (or of HNCO) to H• + NCO• radicals ∼46 kcal/mol above the T0 nitrene. Isofulminic acid, HONC, isomerizes readily to cyanic acid, HOCN, in thermal and photochemical reactions. Fulminic acid, HCNO, can isomerize to HNCO via CSS formylnitrene. Easy tautomerization prevents the preparation of HOCN in quantity. The barrier to isomerization is strongly reduced in small hydrogen-bonded aggregates so that trace amounts of HOCN can exist in equilibrium with HNCO.
- 9 February 2023
- Published by American Physical Society (APS) in Physical Review B
- Vol. 107 (5) , 054407
Coherent description of the magnetic properties of versus temperature and magnetic fieldWe report a combined theoretical and experimental investigation devoted to getting deeper insights into the exotic magnetic properties of the low-dimensional system, for which the two inequivalent Cu(1) and Cu(2) sites show different quantum dynamics. First-principles calculations based on the density functional theory were performed to extract the magnetic exchange couplings. Briefly, we notably find that (i) the magnetic structure can be decomposed into two subsystems made of strongly antiferromagnetically coupled Cu(1) singlet state dimers and weak antiferromagnetic Cu(2) spin chains and (ii) weak ferromagnetic interactions between the two subsystems lead to magnetic frustration. The present model allows us to reproduce both magnetic susceptibility and torque magnetometry measurements. In addition, high-magnetic-field experiments and density-matrix renormalization-group simulations evidence a half-magnetization plateau at 40–45 T associated with the polarization of the Cu(2) spin chains, while the Cu(1) dimers are expected to reach the triplet state at 210–220 T.- 9 February 2023
- Published by American Physical Society (APS) in Physical Review B
- Vol. 107 (5) , 054407
Coherent description of the magnetic properties of versus temperature and magnetic fieldWe report a combined theoretical and experimental investigation devoted to getting deeper insights into the exotic magnetic properties of the low-dimensional system, for which the two inequivalent Cu(1) and Cu(2) sites show different quantum dynamics. First-principles calculations based on the density functional theory were performed to extract the magnetic exchange couplings. Briefly, we notably find that (i) the magnetic structure can be decomposed into two subsystems made of strongly antiferromagnetically coupled Cu(1) singlet state dimers and weak antiferromagnetic Cu(2) spin chains and (ii) weak ferromagnetic interactions between the two subsystems lead to magnetic frustration. The present model allows us to reproduce both magnetic susceptibility and torque magnetometry measurements. In addition, high-magnetic-field experiments and density-matrix renormalization-group simulations evidence a half-magnetization plateau at 40–45 T associated with the polarization of the Cu(2) spin chains, while the Cu(1) dimers are expected to reach the triplet state at 210–220 T.- Open Access
- 25 July 2022
- Published by Wiley in Advanced Optical Materials
- Vol. 10 (21)
Tuning of Thermometric Performances of Mixed Eu–Tb Metal–Organic Frameworks through Single‐Crystal Coordinating Solvent Exchange Reactions
An initial investigation on the employment of targeted structural alterations, achieved through the post‐synthesis modification method, for modulation of the thermometric properties of metal–organic frameworks (MOFs) is reported. The MOF Eu0.05Tb0.95‐NBDC (NBDC = 2‐amino‐1,4‐benzenedicarboxylate) is chosen as pristine material, and its terminal N,N‐dimethylformamide (DMF) molecules are exchanged by various terminal and chelating ligands through a single‐crystal‐to‐single‐crystal coordinating solvent exchange reaction. Temperature‐dependence luminescence studies reveal that all samples are highly sensitive in the medium range with a maximum relative sensitivity of 2.6% K−1 at 190 K for Eu0.05Tb0.95‐NBDC. In addition, a shift of 50 K of the operating temperature range is evidenced for the exchanged analogs. This is attributed to the occurrence of different deactivation pathways in the exchanged analogs due to the presence of N‐donor terminal or N/O‐donor chelating aromatic ancillary ligands in the place of DMF terminal ligands in the pristine material. Overall, this work provides insights into the role of terminal and chelating ligands on the thermometric properties of mixed Eu–Tb MOFs and proposes a promising strategy to control and modulate their thermometric performances.
- 25 July 2022
- Published by Wiley in Advanced Optical Materials
- Vol. 10 (21)
Open AccessTuning of Thermometric Performances of Mixed Eu–Tb Metal–Organic Frameworks through Single‐Crystal Coordinating Solvent Exchange Reactions
An initial investigation on the employment of targeted structural alterations, achieved through the post‐synthesis modification method, for modulation of the thermometric properties of metal–organic frameworks (MOFs) is reported. The MOF Eu0.05Tb0.95‐NBDC (NBDC = 2‐amino‐1,4‐benzenedicarboxylate) is chosen as pristine material, and its terminal N,N‐dimethylformamide (DMF) molecules are exchanged by various terminal and chelating ligands through a single‐crystal‐to‐single‐crystal coordinating solvent exchange reaction. Temperature‐dependence luminescence studies reveal that all samples are highly sensitive in the medium range with a maximum relative sensitivity of 2.6% K−1 at 190 K for Eu0.05Tb0.95‐NBDC. In addition, a shift of 50 K of the operating temperature range is evidenced for the exchanged analogs. This is attributed to the occurrence of different deactivation pathways in the exchanged analogs due to the presence of N‐donor terminal or N/O‐donor chelating aromatic ancillary ligands in the place of DMF terminal ligands in the pristine material. Overall, this work provides insights into the role of terminal and chelating ligands on the thermometric properties of mixed Eu–Tb MOFs and proposes a promising strategy to control and modulate their thermometric performances.
- Open Access
- 12 May 2022
- Published by MDPI AG in Computation
- Vol. 10 (5) , 73
Influence of the Chemical Pressure on the Magnetic Properties of the Mixed Anion Cuprates Cu2OX2 (X = Cl, Br, I)
In this study, we theoretically investigate the structural, electronic and magnetic properties of the Cu2OX2 (X = Cl, Br, I) compounds. Previous studies reported potential spin-driven ferroelectricity in Cu2OCl2, originating from a non-collinear magnetic phase existing below ∼70 K. However, the nature of this low-temperature magnetic phase is still under debate. Here, we focus on the calculation of J exchange couplings and enhance knowledge in the field by (i) characterizing the low-temperature magnetic order for Cu2OCl2 and (ii) evaluating the impact of the chemical pressure on the magnetic interactions, which leads us to consider the two new phases Cu2OBr2 and Cu2OI2. Our ab initio simulations notably demonstrate the coexistence of strong antiferromagnetic and ferromagnetic interactions, leading to spin frustration. The Néel temperatures were estimated on the basis of a quasi-1D AFM model using the J couplings. It nicely reproduces the value for Cu2OCl2 and allows us to predict an increase of under chemical pressure, with = 120 K for the dynamically stable phase Cu2OBr2. This investigation suggests that chemical pressure is an effective key factor to open the door of room-temperature multiferroicity.- 12 May 2022
- Published by MDPI AG in Computation
- Vol. 10 (5) , 73
Open AccessInfluence of the Chemical Pressure on the Magnetic Properties of the Mixed Anion Cuprates Cu2OX2 (X = Cl, Br, I)
In this study, we theoretically investigate the structural, electronic and magnetic properties of the Cu2OX2 (X = Cl, Br, I) compounds. Previous studies reported potential spin-driven ferroelectricity in Cu2OCl2, originating from a non-collinear magnetic phase existing below ∼70 K. However, the nature of this low-temperature magnetic phase is still under debate. Here, we focus on the calculation of J exchange couplings and enhance knowledge in the field by (i) characterizing the low-temperature magnetic order for Cu2OCl2 and (ii) evaluating the impact of the chemical pressure on the magnetic interactions, which leads us to consider the two new phases Cu2OBr2 and Cu2OI2. Our ab initio simulations notably demonstrate the coexistence of strong antiferromagnetic and ferromagnetic interactions, leading to spin frustration. The Néel temperatures were estimated on the basis of a quasi-1D AFM model using the J couplings. It nicely reproduces the value for Cu2OCl2 and allows us to predict an increase of under chemical pressure, with = 120 K for the dynamically stable phase Cu2OBr2. This investigation suggests that chemical pressure is an effective key factor to open the door of room-temperature multiferroicity. - 3 January 2022
- Published by Royal Society of Chemistry (RSC) in Physical Chemistry Chemical Physics
- Vol. 24 (4) , 2482-2490
First-principles calculations to identify key native point defects in Sr 4 Al 14 O 25
This article reports for the first time an in-depth ab initio computational study on intrinsic point defects in Sr 4 Al 14 O 25 that serves as host lattice for numerous phosphors.
- 3 January 2022
- Published by Royal Society of Chemistry (RSC) in Physical Chemistry Chemical Physics
- Vol. 24 (4) , 2482-2490
First-principles calculations to identify key native point defects in Sr 4 Al 14 O 25
This article reports for the first time an in-depth ab initio computational study on intrinsic point defects in Sr 4 Al 14 O 25 that serves as host lattice for numerous phosphors.