Odd-Parity Multipoles by Staggered Magnetic Dipole and Electric Quadrupole Orderings in CeCoSi

CeCoSi的从头算Wannier模型中的RKKY相互作用与多极矩序

RKKY Interactions and Multipole Order in Ab initio Wannier Model of CeCoSi

基于从头算计算CeCoSi的RKKY相互作用，在随机相位近似下研究发现单极矩和十六极矩的非磁性反铁多极矩序，可解释部分实验。

NQR and NMR spectra in odd-parity multipole material CeCoSi

We theoretically study NQR and NMR spectra in the presence of odd-parity multipoles originating from staggered antiferromagnetic and antiferroquadrupole orderings. For the $f$-electron metal, CeCoSi, which is a candidate hosting odd-parity multipoles, we derive an effective hyperfine field acting on Co nucleus generated from electronic origin multipole moments at Ce ion under zero and nonzero magnetic fields. We elucidate that emergent odd-parity multipoles give rise to sublattice-dependent spectral splittings in NQR and NMR through the effective hyperfine coupling in the absence of the global…

利用 $^{59}$Co-NMR 测量揭示 CeCoSi 中的铁性四极有序

Ferroic quadrupolar ordering in CeCoSi revealed using $^{59}$Co-NMR measurements

通过 $^{59}$Co-NMR 测量研究 CeCoSi 在约 12 K 的非磁性相变，提出并证实其为铁性 $O_{zx}$ 型四极有序。

Emergent odd-parity multipoles and magnetoelectric effects on a diamond structure: implication to 5$d$ transition metal oxides $A$OsO$_4$ ($A=$ K, Rb, and Cs)

We report our theoretical predictions on the linear magnetoelectric (ME) effects originating from odd-parity multipoles associated with spontaneous spin and orbital ordering on a diamond structure. We derive a two-orbital model for $d$ electrons in $e_g$ orbitals by including the effective spin-orbit coupling which arises from the mixing between $e_g$ and $t_{2g}$ orbitals. We show that the model acquires a net antisymmetric spin-orbit coupling once staggered spin and orbital orders occur spontaneously. The staggered orders are accompanied by odd-parity multipoles: magnetic monopole, quadrupol…

Multipole Orders in a Chain Ferrate Na2FeSe

Fundamental block and staggered orders of magnetic Fe multipoles in Na2FeSe2 are classified by their symmetry and magnetoelectric properties. Our structure model incorporates ferromagnetic or antiferromagnetic coupling between chains. The ferrate salt is valued in studies of highly correlated electrons as the only iron selenide known to possess chain-like structural units hosting ferrous cations. Axial and polar (Dirac) multipoles are compulsory in the electronic structure since Fe ions exhibit enantiomorphic symmetry in the parent K2ZnO2-type compound. Calculated Bragg diffraction patterns fo…

Electric octupole order in bilayer Rashba system

The odd-parity multipole is an emergent degree of freedom, leading to spontaneous inversion symmetry breaking. The odd-parity multipole order may occur by forming staggered even-parity multipoles in a unit cell. We focus on a locally noncentrosymmetric bilayer Rashba system, and study an odd-parity electric octupole order caused by the antiferro stacking of local electric quadrupoles. Analyzing the forward scattering model, we show that the electric octupole order is stabilized by a layer-dependent Rashba spin-orbit coupling. The roles of the spin-orbit coupling are clarified on the basis of t…