First Observed Metal-like to Insulator Transition in the Vacant 3d Orbital Quantum-Spin Liquid Tb2Ti2O7

• Published in: Journal of physical chemistry. C Vol. 124; no. 46; pp. 25175 - 25183
• Main Authors: Santhosh Kumar, B, Venkateswaran, C
• Format: Journal Article
• Language: English
• Published: American Chemical Society 19.11.2020
• Subjects: C: Energy Conversion and Storage; Energy and Charge Transport
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.0c05174

We report the observation of metal-like to insulator transition (MTI) in the 3d pyrochlore oxide Tb2Ti2O7 at 603 K due to the interaction of empty 3d orbitals of Ti4+ with O2– ions, evidenced by the transition in resistivity. Magnetization, specific heat capacity, and differential scanning calorimetry support the MTI, and the transition is of second order. An appreciable change in magnetization with temperature, without any magnetic phase transition, is a behavior typical in this family of compounds, which is seldom observed in empty d orbital pyrochlores. The possible mechanism that supports the MTI in Tb2Ti2O7 is discussed. Subsequently, a broad change in magnetization from 696 K is also seen. Thermogravimetric analysis confirms the observed MTI (603 K) and the broad change in magnetization (696 K) are not due to oxygen vacancy.