In a quantum spin trimer system with half-integer spin, each trimer has a spin-1/2 responsible for magnetism and a pseudospin-1/2 responsible for electric polarization and scalar chirality, and their interplay is expected to induce a variety of different phases and multiferroic phenomena [1]. Although there are few experimental realizations compared to the well-studied quantum spin dimer systems, trimer systems have been realized in the so-called breathing kagome lattice and organic magnetic materials based on molecular magnets. In this informal talk, we will discuss our ongoing study of magnetization processes in the trimerized triangular lattice Heisenberg model using a semiclassical approach [2]. Despite only nearest-neighbor interactions, a series of incommensurate phases with field-dependent wavelengths are suggested over a wide range of external fields. Interestingly, the instability of a 1/3 magnetization plateau may be caused by a mechanism completely different from the well-known magnon BEC.

References:
[1] Y. Kamiya and C. D. Batista, Phys. Rev. Lett. 108, 097202 (2012).
[2] Z. Zhang and Y. Kamiya, in preparation.

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