Minoru Yamashita : Magnetization of Dipole-Octupole QSI candidate Ce2Hf2O7 

Minoru Yamashita (University of Tokyo, actuellement visiteur dans l’équipe SQM)

Abstract

I will present our magnetization study done in the dipole-octupole quantum spin ice (DO-QSI) candidate Ce2Hf2O7. I shall begin my talk from a general introduction of a quantum spin liquid, particularly the motivation for the research. Then, I will talk about a recent topic of a new quantum spin liquid, symmetry-enriched DO-QSIs, which is suggested to be realized in Ce-based pyrochlores by introducing a pseudo-spin doublet of the total angular momentum |J| = 5/2. To identify the ground state, we performed comprehensive magnetization measurements down to 50 mK in a high-quality single crystal of Ce2Hf2O7 along all the principal axes of the pyrochlore structure [1]. We find a kink anomaly in the magnetization measured under the magnetic field B || [111] that appears below 300 mK, concomitantly with a development of a magnetic hysteresis.
Our classical Monte-Carlo and quantum exact diagonalization calculations demonstrate that the magnetization curves, including the kink anomaly under B || [111], are well reproduced by the spin-interaction parameters with a dominant octupole interaction and with a QSI ground state, providing direct evidence of an octupole-based QSI in this material. I will also talk about my experimental plan during my stay in LPS.

[1] E. Kermarrec, M.Y. et al. arXiv:2509.09189