We present a detailed study on the structural phase transition in α-TiBr3, which is deeply connected with the lattice and orbital degree of freedoms. A chemical vapor transport method is adopted to synthesize the α-TiBr3 single crystal samples, and the structural phase transition at about 180 K is characterized by x-ray diffraction (XRD), magnetic susceptibility, and specific heat capacity. To further the understanding in the physical nature of this phase transition, a systematic Raman spectroscopic study is performed on α-TiBr3 crystals. With temperature decreasing, a large frequency blue shift and peak width narrowing are observed in the vibrational mode associated with Ti in-plane relative movement, which indicates the formation of Ti–Ti bonding and orbital-fluctuation freezing at low temperatures. These results are fully consistent with magnetic–nonmagnetic phase transition resolved by the measurement of magnetic susceptibility and lattice changes by XRD.
Orbital-fluctuation freezing and magnetic-nonmagnetic phase transition in α-TiBr3
Shenghai Pei, Jiangke Tang, Cai Liu, Jia-Wei Mei, Zenglong Guo, Bingbing Lyu, Naipeng Zhang, Qiaoling Huang, Dapeng Yu, Li Huang, Junhao Lin, Le Wang, Mingyuan Huang; Orbital-fluctuation freezing and magnetic-nonmagnetic phase transition in α-TiBr3. Appl. Phys. Lett. 28 September 2020; 117 (13): 133103. https://doi.org/10.1063/5.0023175
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