Ganesh Adhikary

In the series R ₂ PdSi ₃ , Nd ₂ PdSi ₃ is an anomalous compound in the sense that it exhibits ferromagnetic order unlike other members in this family. The magnetic ordering temperature is also unusually high compared to the expected value for a Nd-based system, assuming 4 f localization. Here, we have studied the electronic structure of single crystalline Nd ₂ PdSi ₃ employing high resolution photoemission spectroscopy and ab initio band structure calculations. Theoretical results obtained for the effective on-site Coulomb energy of 6 eV corroborate well with the experimental valence band spectra. While there is significant Pd 4 d –Nd 4 f hybridization, the states near the Fermi level are found to be dominated by hybridized Nd 4 f –Si 3 p states, which is possibly responsible for the ferromagnetism in Nd compound. Nd 3 d core level spectrum exhibits multiple features manifesting strong final state effects due to electron correlation, charge transfer and collective excitations. These results serve as one of the rare demonstrations of hybridization of Nd 4 f states with the conduction electrons possibly responsible for the exoticity of this compound.

Optical vortices are currently one of the most intensively studied topics in optics. These light beams, which carry orbital angular momentum (OAM), have been successfully utilized in the visible and infrared in a wide variety of applications. Moving to shorter wavelengths may open up completely new research directions in the areas of optical physics and material characterization. Here, we report on the generation of extreme-ultraviolet optical vortices with femtosecond duration carrying a controllable amount of OAM. From a basic physics viewpoint, our results help to resolve key questions such as the conservation of angular momentum in highly nonlinear light–matter interactions, and the disentanglement and independent control of the intrinsic and extrinsic components of the photon’s angular momentum at short-wavelengths. The methods developed here will allow testing some of the recently proposed concepts such as OAM-induced dichroism, magnetic switching in organic molecules and violation of dipolar selection rules in atoms.

The electronic structure of off-stoichiometric Ni₂Mn_1+xSn_1-x (x = 0.44, 0.48, 0.52) Heusler alloys as a function of composition is studied by x-ray photoelectron spectroscopy at 10 K. The extra Mn is substituted at Sn site. The Ni 2p, Mn 3s, Sn 4d core-levels and valence band are probed. The results show that Mn core-levels are affected by Mn concentration, whereas Ni, Sn core-levels and valence band are un-affected.

New strategy for room temperature magnetic gas sensing based on magnetoelectrically-coupled hybrids. The sensor is sensitive, fast and cost-effective. The sensing is allowed thanks to the magneto-electric coupling at the interface.