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arXiv · 2207.09075

Field-orientation dependence of quantum phase transitions in the S=1/2 triangular-lattice antiferromagnet Ba$_3$CoSb$_2$O$_9$

Kazuki Okada·Hidekazu Tanaka·Nobuyuki Kurita·Daisuke Yamamoto·Akira Matsuo·Koichi Kindo
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Abstract

Ba$_3$CoSb$_2$O$_9$ approximates the two-dimensional spin-1/2 triangular-lattice Heisenberg antiferromagnet. This compound displays magnetic-field-induced quantum phase transitions, including the 1/3-magnetization-plateau, but its magnetization processes for the magnetic field $H$ parallel and perpendicular to the $c$ axis are different due to the weak easy-plane anisotropy and the weak interlayer antiferromagnetic exchange interaction. To elucidate how the quantum phase transitions change between these two field directions, we measured the field-angle dependence of the magnetization process in Ba$_3$CoSb$_2$O$_9$ using pulsed high magnetic fields. We compared obtained magnetic field-field angle phase diagram with those obtained by the large-size cluster mean-field method combined with a scaling scheme and the semiclassical theory. We also found a narrow 1/3-magnetization plateau and a high-field transition with a small magnetization jump for $H\,{\parallel}\,c$, not observed in the previous studies.

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Kazuki Okada, Hidekazu Tanaka, Nobuyuki Kurita, Daisuke Yamamoto, Akira Matsuo, Koichi Kindo. 2022-07-19. Field-orientation dependence of quantum phase transitions in the S=1/2 triangular-lattice antiferromagnet Ba$_3$CoSb$_2$O$_9$. https://doi.org/10.1103/physrevb.106.104415

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