Low-field colossal magnetoresistance in bandwidth-controlled manganites
- Joint Research Center for Atom Technology (JRCAT), Tsukuba 305 (Japan)
We have investigated magnetoresistance (MR) phenomena relevant to the charge ordering (CO), namely, the real space ordering of both Mn{sup 3+} and Mn{sup 4+}, in single crystals of (Nd{sub 1{minus}y}Sm{sub y}){sub 1/2}Sr{sub 1/2}MnO{sub 3}, in which the one-electron bandwidth {ital (W)} is systematically controlled by varying the average ionic radius of the {ital A} site. The low-field colossal MR is observed for the small-{ital W} region of y{ge}0.5; e.g., {rho}(0)/{rho}(H){gt}10{sup 3} in a field of 0.4 T at 115 K for the y=0.94 crystal. This is viewed as a first-order insulator-to-metal phase transition induced by a magnetic field, which accompanies a lattice-structural change. In the small-{ital W} region, the CO instability accompanying the antiferromagnetic spin correlations subsists even above the ferromagnetic transition temperature T{sub c}. The competition between the ferromagnetic double-exchange and antiferromagnetic CO interactions gives rise to such a lattice-coupled first-order phase transition induced by a relatively low magnetic field. {copyright} {ital 1997 American Institute of Physics.}
- OSTI ID:
- 554266
- Report Number(s):
- CONF-961141-; ISSN 0021-8979; TRN: 98:000876
- Journal Information:
- Journal of Applied Physics, Vol. 81, Issue 8; Conference: 41. annual conference on magnetism and magnetic materials, Atlanta, GA (United States), 12-15 Nov 1996; Other Information: PBD: Apr 1997
- Country of Publication:
- United States
- Language:
- English
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