Microscopic mechanism for the unusual antiferromagnetic order and the pressure-induced transition to ferromagnetism in USb2

Abstract

Uranium dipnictide USb2 reflects enigmatic properties posing a substantial challenge for a microscopic modeling. Among others, it develops a nonstandard antiferromagnetic order of a ↑↓↓↑-type along [001] crystallographic direction, and under pressure it undergoes transition to the ferromagnetic phase. Here we propose a minimal low-energy model of USb2 which, as we demonstrate at the mean-field level, accommodates physical mechanism for mentioned observations. Relying on the obtained results we also comment on the features of magnetism observed in other U-based compounds: UAs2, UBi2, UAsSe, URhxIr1−xGe and UGe2. * Electronic address: mwysoki@sissa.it

Mechanism for transitions between ferromagnetic and antiferromagnetic orders in d-electron metallic magnets

“…32 for FM phases and ref. 8 for AFM.). Here 〈…〉 0 denotes an expectation value with the Slater determinant and 〈…〉 G with the Gutzwiller wave function under the Gutzwiller approximation.…”

“…Intuition for the character of each channel separately can be gained by recalling magnetic properties of mentioned earlier, two well-established models: two-band Anderson lattice model 8,32–43 (Eq. (1) with t d = 0) with only 1 st SC present, and single-band Hubbard model 44–49 (Eq.…”

“…Recently, general expectations concerning order of transitions between FM and AFM phases have been provided within extended Landau theory 7 . In turn, the generic microscopic mechanisms triggering such transitions, except material specific ones 8,9 , are mostly unidentified. The effective action approach incorporating corrections due to quantum fluctuations 10,11 constitutes a notable exception.…”

Valence instability across the magnetostructural transition in USb2

“…[8] Pressure-dependent transport measurements performed on USb 2 indicate that T N approaches that of UAs 2 , but an abrupt AFM-FM transition occurs near P=8 GPa, reducing the ordering temperature by over 100 K. [9] The AFM-FM transition has been the subject of several recent theoretical calculations, though from an experimental standpoint, only little is known about this transition. [10,11] Based on structural tetragonal to orthorhombic transitions in the related UAsS, UP 2 , and UAs 2 structures at 46 GPa, 22 GPa, and 15 GPa, respectively, it stands to reason that USb 2 may undergo a coupled magnetostructural transition. [12] The U foccupancy, n f , may also be affected by such a magnetostructural transition and could play a fundamental role in dictating the magnetic structure.…”