1. Geballe Laboratory for Advanced Materials, Department of Physics and Department of Applied Physics, Stanford University, CA 94305, USA.
2. Cross-Correlated Materials Group (CMRG) and Correlated Electron Research Group (CERG), RIKEN, Advanced Science Institute (ASI), Wako 351-0198, Japan.
3. WPI–Advanced Institute for Materials Research (AIMR), Tohoku University, Sendai 980-8577, Japan.
4. Department of Applied Physics, University of Tokyo, Tokyo 113-8586, Japan.