Spin-phonon interaction and band effects in the high-TcsuperconductorHgBa2CuO4

Band calculations show that a stripelike antiferromagnetic spin wave is enforced by a “half-breathing” phonon distortion within the CuO plane of ${\mathrm{HgBa}}_2{\mathrm{CuO}}_4.$ This spin-phonon coupling is increased further by shear distortion and by the increased distance between Cu and apical oxygens. The effects from spin-phonon coupling are consistent with many observations in high-$T_c$ materials. Spin-phonon coupling can be important for the mechanism of spin fluctuations and superconductivity, although the effects are quantitatively weak when using the local density potential.