%0 Journal Article
%A Bhobe, P. A.
%A Kumar, A.
%A Taguchi, M.
%A Eguchi, R.
%A Matsunami, M.
%A Takata, Y.
%A Nandy, Ashis Kumar
%A Mahadevan, P.
%A Sarma, D. D.
%A Neroni, A.
%A Şaşıoğlu, E.
%A Ležaić, M.
%A Oura, M.
%A Senba, Y.
%A Ohashi, H.
%A Ishizaka, K.
%A Okawa, M.
%A Shin, S.
%A Tamasaku, K.
%A Kohmura, Y.
%A Yabashi, M.
%A Ishikawa, T.
%A Hasegawa, K.
%A Isobe, M.
%A Ueda, Y.
%A Chainani, A.
%T Electronic Structure Evolution across the Peierls Metal-Insulator Transition in a Correlated Ferromagnet
%J Physical review / X
%V 5
%N 4
%@ 2160-3308
%C College Park, Md.
%I APS
%M FZJ-2015-06979
%P 041004
%D 2015
%X 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.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000362489800001
%R 10.1103/PhysRevX.5.041004
%U https://juser.fz-juelich.de/record/276651