”Low-dimensional frustrated magnets with competing ferromagnetic and antiferromagnetic interactions” Kazuhiro Nawa (ISSP)

Theory of Quantum Matter Unit would like to invite you to a seminar :

• Title: Low-dimensional frustrated magnets with competing ferromagnetic and antiferromagnetic interactions
• Speaker: Dr. Kazuhiro Nawa (ISSP, University of Tokyo)
• Date: Tue, 21st Oct
• Time: 14:00-15:00
• Venue: C016, Lab1

Low-dimensional frustrated magnets with competing ferromagnetic and antiferromagnetic interactions

Kazuhiro Nawa (ISSP, The University of Tokyo)

Frustrating interactions and quantum fluctuations in low dimensional spin systems prevent conventional magnetic order and can lead to unconventional magnetic order or exotic ground states. A lot of theoretical and experimental studies have been focused on low-dimensional frustrated magnets such as triangular and kagome antiferromagnets with competing antiferromagnetic interactions. Recently, it is going to be recognized that exotic ground states can be also realized in low-dimensional frustrated magnets with competing ferromagnetic and antiferromagnetic interactions. For example, a spin-nematic state is theoretically expected in a one-dimensional frustrated J1-J2 chain magnet, where the nearest-neighbor interaction J1 becomes ferromagnetic while the next-nearest neighbor interaction J2 is antiferromagnetic [1, 2]. Besides, a cuboc order may be present in a kagome-triangular (KT) magnet, where the kagome lattice connected by ferromagnetic J1 is deformed so as to generate antiferromagnetic J2 between three out of six spins in the hexagon of a normal kagome lattice [3]. We show that NaCuMoO4(OH) [4] and NaBa2Mn3F11 [3] can be candidates of the J1-J2 chain magnet and the KT magnet, respectively, and discuss their possible ground states through magnetization, heat capacity and nuclear magnetic resonance (NMR) spectroscopy measurements.

[1] T. Vekua, A. Honecker, H.-J. Mikeska, and F. Heidrich-Meisner, Phys. Rev. B, 76, 174420 (2007). 
[2] T. Hikihara, L. Kecke, T. Momoi, and A. Furusaki, Phys. Rev. B, 78, 144404 (2008). 
[3] H. Ishikawa, T. Okubo, Y. Okamoto, and Z. Hiroi, J. Phys. Soc. Jpn., 83, 043703 (2014).  
[4] K. Nawa, Y. Okamoto, A. Matsuo, K. Kindo, Y. Kitahara, S. Yoshida, S. Ikeda, S. Hara, T. Sakurai, S. Okubo, H. Ohta, and Z. Hiroi, J. Phys. Soc. Jpn., 83, 103702 (2014).