Spin-charge-lattice coupled phase transitions in bandwidth-controlled systems: (Nd,Sm){sub 1/2}Sr{sub 1/2}MnO{sub 3}

Journal Article · Wed Oct 01 04:00:00 EDT 1997 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.56.9386· OSTI ID:543814

Kuwahara, H; Moritomo, Y; Tomioka, Y; Asamitsu, A; Kasai, M; Kumai, R ^[1]; Tokura, Y ^[1]

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1. Joint Research Center for Atom Technology (JRCAT), Tsukuba 305 (Japan)

The metal-insulator (M-I) phase transitions relevant to charge ordering (CO) have been investigated for perovskite-type (Nd{sub 1{minus}y}Sm{sub y}){sub 1/2}Sr{sub 1/2}MnO{sub 3} (0{le}y{le}1) crystals, in which the one-electron bandwidth (W) is systematically controlled by varying the averaged ionic radius of the A site and by application of quasihydrostatic pressure (P). Competition between the ferromagnetic double exchange and the antiferromagnetic CO interactions give rise to complex M-I phase diagrams with temperature (T) and W (y and/or P) as the parameters. The M-I phase boundaries are associated with critically W- and T-dependent hystereses, which result in unique appearance of the metastable state. We have demonstrated the pressure-induced phase transition from the metastable ferromagnetic metal to the thermodynamically stable charge-ordered insulator for the y=0.875 crystal locating near the critical M-I phase boundary. With decrease of W, the CO instability accompanying the antiferromagnetic spin correlations subsists even above the ferromagnetic transition temperature (T{sub c}) and enhances the electron-lattice coupling. Consequently, the lattice-coupled first-order I-M transition is observed at T{sub c} in the small-W region of y{ge}0.5. It was found that application of magnetic field also induces the phase transition from the insulator with antiferromagnetic spin correlations to the ferromagnetic metal, which is accompanied by lattice-structural change. {copyright} {ital 1997} {ital The American Physical Society}

• OSTI ID: 543814
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 15 Vol. 56; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANTIFERROMAGNETIC MATERIALS
CHARGE DISTRIBUTION
ELECTRIC CONDUCTIVITY
ELECTRICAL INSULATORS
EXCHANGE INTERACTIONS
FERRIMAGNETIC MATERIALS
FERROMAGNETIC MATERIALS
MANGANESE OXIDES
NEODYMIUM OXIDES
PEROVSKITES
PHASE TRANSFORMATIONS
PRESSURE DEPENDENCE
SAMARIUM OXIDES
STRONTIUM OXIDES