INSULATOR-METAL TRANSITION AND GIANT MAGNETORESISTANCE IN LA1-XSRXMNO3
INSULATOR-METAL TRANSITION AND GIANT MAGNETORESISTANCE IN LA1-XSRXMNO3
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DOI：
10.1103/physrevb.51.14103
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发表时间：
1995-05-15
影响因子：
3.7
通讯作者：
TOKURA, Y
中科院分区：
文献类型：
--
作者：
URUSHIBARA, A;MORITOMO, Y;TOKURA, Y
对于典型的双交换铁磁体，即La 1− x Sr x MnO 3（0≤ x≤ 0.6）晶体，研究了依赖于能带填充（掺杂度）、温度和外部磁场的绝缘体-金属现象。通过对熔体生长晶体的磁、电测量，推导出了温度与名义空穴浓度（x）平面内的电子相图。在铁磁转变温度TC附近，观察到较大的负磁阻效应.无论温度如何，电阻率的降低与场致磁化强度（M）成比例，对于M/Ms ≤ 0.3，为-Δρ/ρ= C（M/Ms）2，其中Ms为饱和磁化强度。系数C强烈地依赖于x，即，在组分绝缘体-金属相边界附近（xc <$0.17），C <$4，但当x>= 0.4时，C下降到C <$1，表明电子状态的临界变化。
Insulator-metal phenomena depending on band filling (doping degree), temperature, and external magnetic field have been investigated for prototypical double-exchange ferromagnets, namely, crystals of La 1− x Sr x MnO 3 (0≤ x≤ 0.6). The electronic phase diagram in the plane of the temperature vs nominal hole concentration (x) has been deduced from the magnetic and electrical measurements on the melt-grown crystals. Around the ferromagnetic transition temperature T C, large negative magnetoresistance was observed. Irrespective of temperature, reduction of the resistivity is scaled with the field-induced magnetization (M) as-Δρ/ρ= C (M/M s) 2 for M/M s≲ 0.3, where M s is the saturated magnetization. The coefficient C strongly depends on x, ie, C≊ 4 near the compositional insulator-metal phase boundary (x c∼ 0.17), but decreases down to≊ 1 for x>= 0.4, indicating the critical change of the electronic state.