TY  - JOUR
AU  - Bhobe, P. A.
AU  - Kumar, A.
AU  - Taguchi, M.
AU  - Eguchi, R.
AU  - Matsunami, M.
AU  - Takata, Y.
AU  - Nandy, Ashis Kumar
AU  - Mahadevan, P.
AU  - Sarma, D. D.
AU  - Neroni, A.
AU  - Şaşıoğlu, E.
AU  - Ležaić, M.
AU  - Oura, M.
AU  - Senba, Y.
AU  - Ohashi, H.
AU  - Ishizaka, K.
AU  - Okawa, M.
AU  - Shin, S.
AU  - Tamasaku, K.
AU  - Kohmura, Y.
AU  - Yabashi, M.
AU  - Ishikawa, T.
AU  - Hasegawa, K.
AU  - Isobe, M.
AU  - Ueda, Y.
AU  - Chainani, A.
TI  - Electronic Structure Evolution across the Peierls Metal-Insulator Transition in a Correlated Ferromagnet
JO  - Physical review / X
VL  - 5
IS  - 4
SN  - 2160-3308
CY  - College Park, Md.
PB  - APS
M1  - FZJ-2015-06979
SP  - 041004
PY  - 2015
AB  - Transition metal compounds often undergo spin-charge-orbital ordering due to strong electron-electron correlations. In contrast, low-dimensional materials can exhibit a Peierls transition arising from low-energy electron-phonon-coupling-induced structural instabilities. We study the electronic structure of the tunnel framework compound K2Cr8O16, which exhibits a temperature-dependent (T-dependent) paramagnetic-to-ferromagnetic-metal transition at TC=180  K and transforms into a ferromagnetic insulator below TMI=95  K. We observe clear T-dependent dynamic valence (charge) fluctuations from above TC to TMI, which effectively get pinned to an average nominal valence of Cr+3.75 (Cr4+∶Cr3+ states in a 3∶1 ratio) in the ferromagnetic-insulating phase. High-resolution laser photoemission shows a T-dependent BCS-type energy gap, with 2G(0)∼3.5(kBTMI)∼35  meV. First-principles band-structure calculations, using the experimentally estimated on-site Coulomb energy of U∼4  eV, establish the necessity of strong correlations and finite structural distortions for driving the metal-insulator transition. In spite of the strong correlations, the nonintegral occupancy (2.25 d−electrons/Cr) and the half-metallic ferromagnetism in the t2g up-spin band favor a low-energy Peierls metal-insulator transition.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000362489800001
DO  - DOI:10.1103/PhysRevX.5.041004
UR  - https://juser.fz-juelich.de/record/276651
ER  -