Magnetic-field-induced effects in the electronic structure of itinerant d- and f-metal systems

Abstract

A paramagnetic response of transition metals and itinerant d-and f -metal compounds in an external magnetic field is studied by employing ab initio full-potential LMTO method in the framework of the local spin density approximation. Within this method the anisotropy of magnetic susceptibility in hexagonal close-packed transition metals is evaluated for the first time. This anisotropy is owing to the orbital Van Vleck-like paramagnetic susceptibility, which is revealed to be substantial in transition metal systems due to hybridization effects in electronic structure. It is demonstrated, that compounds TiCo, Ni 3 Al, YCo 2 , CeCo 2 , YNi 5 , LaNi 5 and CeNi 5 are strong paramagnets close to the quantum critical point. For these systems the Stoner approximation underestimates the spin susceptibility, whereas the calculated field-induced spin moments provided a good description of the large paramagnetic susceptibilities and magnetovolume effects. It is revealed, that itinerant description of hybridized f electrons produces magnetic properties of CeCo 2 , CeNi 5 , UAl 3 , UGa 3 , USi 3 and UGe 3 compounds in close agreement with experiment. In the uranium UX 3 compounds the strong spin-orbit coupling together with hybridization effects give rise to peculiar magnetic states, where the field-induced spin moments are antiparallel to the external field and the magnetic response is dominated by the orbital contribution.

Interrelation of superconductivity and magnetism in FeSe1−xTex compounds. Pressure effects

“…As can be seen from the values of pressure derivative of susceptibility, d lnχ/dP , given in Table II, for considered FeSe(Te) system the pressure effect not only much exceeds its typical value in the exchange-enhanced itinerant paramagnets [31], but also has the opposite positive sign. This implies an unusual for metallic system possibility of transition to the ferromagnetic state under the influence of experimentally achievable pressures.…”

“…As is evident from the presented data, the pressure effects on T c in the tellurium rich FeSe 1−x Te x compounds are comparable in magnitude with that for FeSe but have opposite negative sign. [30,31]). The exchange-correlation potential was treated within the local density approximation (LDA [32]) of the density functional theory (DFT).…”

“…[31] within the local spin density approximation (LSDA) of DFT. The relativistic effects, including spinorbit coupling, were incorporated, and the effect of an external magnetic field B was taken into account selfconsistently by means of the Zeeman term:…”

Magnetic properties of Mn-doped Bi2Se3compound: temperature dependence and pressure effects

“…The calculations were performed by employing a relativistic full-potential LMTO method (FP-LMTO, RSPt code [46][47][48]) within the generalized gradient approximation [49] of the density functional theory. The effective mass of electrons was obtained using a parabolic band model at the conduction band minimum by a parabolic fitting to the band dispersion E(k) along different directions around the Γ symmetry point of the Brillouin zone (see figure 6) and employing the relation (14).…”

Electronic Structure and Magnetic Properties of FeTe, BiFeO3, SrFe12O19 and SrCoTiFe10O19 Compounds

“…The self-consistent calculations of electronic structures were carried out by using the modified relativistic LMTO method with a full potential (FP-LMTO, RSPt implementation [16][17][18]) and the linearized augmented plane waves method with a full potential (FP-LAPW, Elk implementation [19]). Exchange and correlation potentials were treated within the generalized gradient approximation (GGA [20]) of DFT.…”