TY - JOUR
T1 - Unconventional magnetic excitations and spin dynamics of exotic quantum spin systems BaCo 2 V 2 O 8 and Ba 3 CuSb 2 O 9
AU - Han, Yibo
AU - Kimura, Shojiro
AU - Okunishi, Kouichi
AU - Hagiwara, Masayuki
N1 - Funding Information:
SK, KO, and MH are grateful to Z. He, T. Taniyama, and M. Itoh for the collaboration of ESR studies of BaCoVO, as well as to T. Takeuchi, M. Matsuda, and T. Masuda for the useful discussions. YH and MH thank T. Nakano, Y. Nozue, K. Kimura, M. Halim, and S. Nakatsuji for their collaboration with ESR studies of BaCuSbO and H. Sawa, N. Katayama, Y. Wakabayashi, S. Ishihara, C. Broholm, K. Kuga, and J. Nasu for the meaningful discussions. This study was partly supported by a Grant-in-Aid for Science Research from the Japanese Ministry of Education, Science, Sports, Culture, and Technology (Nos. 17072005, 1874018, 1870230, 24244059, 27505030). We would like to thank Editage (www.editage.com) and M.W. Meisel for English language editing.
Publisher Copyright:
© 2020, Springer-Verlag GmbH Austria, part of Springer Nature.
PY - 2020
Y1 - 2020
N2 - We review terahertz (THz) electron spin resonance studies of two types of exotic quantum spin systems, namely, the spin(S)-1/2 one-dimensional (1D) Ising-like antiferromagnet BaCo2V2O8 and the S=1/2 two-dimensional (2D) honeycomb-like antiferromagnet Ba3CuSb2O9 in magnetic fields of up to 50 T. For the former subject, unconventional magnetic excitations were identified below a critical magnetic field Hc(∼ 4 T), where the exotic field-induced order-to-disorder transition occurs, and magnetic excitations in a Tomonaga-Luttinger liquid state were observed above Hc. The novel magnetic excitations were analyzed with an S=1/2 1D XXZ model by considering the peculiar structure of this compound. For the latter subject, the orbital quantum dynamics of the spin liquid candidate Ba3CuSb2O9 was revealed using multifrequency electron spin resonance ranging from 9.3 GHz to 0.73 THz. The g-factor of the hexagonal Ba3CuSb2O9 single crystal possesses a weak six-fold symmetry at low frequencies, while two-fold symmetry is manifested at high frequencies. From the critical point between the two frequency regions, the frequency of the dynamic Jahn-Teller distortion is determined to be approximately 10 GHz. This dynamic distortion, accompanied by orbital quantum tunneling, proves the spin-orbital liquid state in Ba3CuSb2O9.
AB - We review terahertz (THz) electron spin resonance studies of two types of exotic quantum spin systems, namely, the spin(S)-1/2 one-dimensional (1D) Ising-like antiferromagnet BaCo2V2O8 and the S=1/2 two-dimensional (2D) honeycomb-like antiferromagnet Ba3CuSb2O9 in magnetic fields of up to 50 T. For the former subject, unconventional magnetic excitations were identified below a critical magnetic field Hc(∼ 4 T), where the exotic field-induced order-to-disorder transition occurs, and magnetic excitations in a Tomonaga-Luttinger liquid state were observed above Hc. The novel magnetic excitations were analyzed with an S=1/2 1D XXZ model by considering the peculiar structure of this compound. For the latter subject, the orbital quantum dynamics of the spin liquid candidate Ba3CuSb2O9 was revealed using multifrequency electron spin resonance ranging from 9.3 GHz to 0.73 THz. The g-factor of the hexagonal Ba3CuSb2O9 single crystal possesses a weak six-fold symmetry at low frequencies, while two-fold symmetry is manifested at high frequencies. From the critical point between the two frequency regions, the frequency of the dynamic Jahn-Teller distortion is determined to be approximately 10 GHz. This dynamic distortion, accompanied by orbital quantum tunneling, proves the spin-orbital liquid state in Ba3CuSb2O9.
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U2 - 10.1007/s00723-020-01296-w
DO - 10.1007/s00723-020-01296-w
M3 - Review article
AN - SCOPUS:85096008603
JO - Applied Magnetic Resonance
JF - Applied Magnetic Resonance
SN - 0937-9347
ER -