Tomoki Yoshioka | Searcharxiv

arXiv2026

Altermagnetic spin-split Fermi surfaces in CrSb revealed by quantum oscillation measurements

We report a comprehensive quantum oscillation study of the prototypical altermagnet CrSb, combining high-field magnetotransport and torque measurements with DFT + $U$ calculations including spin-orbit coupling. Multiple quantum oscillation frequencies were observed and tracked over wide angular ranges. The measured frequency branches are consistently explained by the spin-split Fermi surfaces arising from the altermagnetic electronic structure. Our determined Fermi surface reveals that bands 1 and 2 form closed pockets centered at the A point, rather than the tubular $c$-axis-open sheets or $\Gamma$-centered closed pockets proposed in previous studies. Our findings establish the Fermi-surface topology of CrSb and provide a firm basis for exploring emergent phenomena in altermagnetic materials.

cond-mat.mtrl-sci↗

arXiv2024

Quantum entanglement in a pure state of strongly correlated quantum impurity systems

We consider quantum entanglement in strongly correlated quantum impurity systems for states manifesting interesting properties such as multi-level Kondo effect and dual nature between itineracy and localization etc.. For this purpose, we set up a system consisting of one or two quantum impurities arbitrarily selected from the system as a subsystem, and investigate quantum entanglement with its environmental system. We reduce the pure state of interest as described above to the subsystem, and formulate quantum informative quantities such as entanglement entropy, mutual information and relative entropy. We apply them to quantum impurity systems consisting of several sites and the single impurity Anderson model to study the relationship between their states and the behaviors of quantum informative quantities. The obtained results suggest that the method proposed here is promising for elucidating the quantum entanglement of pure states in various quantum impurity systems.

cond-mat.str-el↗