5 papers · 1 filter
Riemannian geometric classification and emergent phenomena of magnetic textures
Koki Shinada, Naoto Nagaosa
We propose a new classification of magnetic textures from the viewpoint of differential geometry. Magnetic textures are conventionally classified into collinear, coplanar, and nonc…
Quantum geometric bounds for observables: Linear responses, Drude weight, and orbital magnetization
Koki Shinada, Naoto Nagaosa
The quantum geometric tensor (QGT) provides nontrivial bounds among physical quantities, as exemplified by the metric-curvature inequality. In this paper, we investigate various bo…
Thermodynamic formulation of the spin magnetic octupole moment in bulk crystals
Jun Åiké, Robert Peters, Koki Shinada
The discovery of unconventional antiferromagnets, such as altermagnets, has drawn significant attention to higher-rank magnetic multipoles, particularly magnetic octupoles. Despite…
Nonlinear Magnetoelectric Effect under Magnetic Octupole Order: Its Application to a -Wave Altermagnet and a Pyrochlore Lattice with All-In/All-Out Magnetic Order
Jun Åiké, Koki Shinada, Robert Peters
Extensive investigation has recently been conducted into a new class of antiferromagnetic order known as magnetic octupole order. However, the high rank of octupoles makes it diffi…
Orbital optical activity in noncentrosymmetric metals and superconductors
Koki Shinada, Robert Peters
We present the optical activity induced by the orbital magnetic moment in metals and superconductors using Green's function formalization. We show that an apparent singularity of t…