0000000000988082
AUTHOR
Martha Greenblatt
Electronic Properties, Band Structure, and Fermi Surface Instabilities ofNi1+/Ni2+NickelateLa3Ni2O6, Isoelectronic with Superconducting Cuprates
Electronic structure calculations were performed for the mixed-valent Ni(1+)/Ni(2+) nickelate La3Ni2O6, which exhibits electronic instabilities of the Fermi surface similar to that of the isostructural superconducting La2CaCu2O6 cuprate. La3Ni2O6 shows activated hopping, which fits to Mott's variable-range-hopping model with localized states near the Fermi level. However, a simple local spin density approximation calculation leads to a metallic ground state. The calculations including local density approximation+Hubbard U and hybrid functionals indicate a multiply degenerate magnetic ground state. For electron-doped La2ZrNi2O6, which is isoelectronic with La2CaCu2O6, an antiferromagnetic in…
Pressure-induced magnetic collapse and metallization of TlFe1.6Se2
The crystal structure, magnetic ordering, and electrical resistivity of $\mathrm{TlF}{\mathrm{e}}_{1.6}\mathrm{S}{\mathrm{e}}_{2}$ were studied at high pressures. Below $\ensuremath{\sim}7\phantom{\rule{0.16em}{0ex}}\mathrm{GPa}$, $\mathrm{TlF}{\mathrm{e}}_{1.6}\mathrm{S}{\mathrm{e}}_{2}$ is an antiferromagnetically ordered semiconductor with a $\mathrm{ThC}{\mathrm{r}}_{2}\mathrm{S}{\mathrm{i}}_{2}$-type structure. The insulator-to-metal transformation observed at a pressure of $\ensuremath{\sim}7\phantom{\rule{0.16em}{0ex}}\mathrm{GPa}$ is accompanied by a loss of magnetic ordering and an isostructural phase transition. In the pressure range $\ensuremath{\sim}7.5\text{--}11\phantom{\rule{…
Magnetic and electronic properties of double perovskites and estimation of their Curie temperatures byab initiocalculations
First principles electronic structure calculations have been carried out on ordered double perovskites Sr_2B'B"O_6 (for B' = Cr or Fe and B" 4d and 5d transition metal elements) with increasing number of valence electrons at the B-sites, and on Ba_2MnReO_6 as well as Ba_2FeMoO_6. The Curie temperatures are estimated ab initio from the electronic structures obtained with the local spin-density functional approximation, full-potential generalized gradient approximation and/or the LDA+U method (U - Hubbard parameter). Frozen spin-spirals are used to model the excited states needed to evaluate the spherical approximation for the Curie temperatures. In cases, where the induced moments on the oxy…