Electrical properties of NiS2-xSex single crystals: From Mott insulator to paramagnetic metal.
Electrical properties of NiS2-xSex single crystals: From Mott insulator to paramagnetic metal.
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NiS2-xSex 单晶的电性能：从莫特绝缘体到顺磁金属。
DOI：
10.1103/physrevb.54.17469
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Spalek
中科院分区：
文献类型：
--
作者：
Yao;Honig;Hogan;Kannewurf;Spalek
报道了在0<~ x<~ 0.71范围内测量的Ni S 2− x Se x单晶的电阻率（ρ）和塞贝克系数（α）。总的趋势是随着x的增加，金属丰度增加。在0.38<~ x<~ 0.51的范围内，ρ随温度（T）的升高而明显上升，此时反铁磁绝缘相（或反铁磁金属相）转变为顺磁绝缘相。对α-T曲线的分析表明，在低温绝缘状态下，空穴和电子都参与了电荷输运。它强调的是，在电特性的许多变化发生在黄铁矿晶体结构没有显着的改变，和物理性质大大改变，仅通过调整的阴离子亚晶格，而阳离子亚晶格保持完整。对0.38<~ x<~ 0.55的样品的电输运结果进行了定性解释，其依据是加热样品时，在50-100 K的温度区间内，在向绝缘（半导体）态转变时，Hubbard分裂开始分裂成子带。接近金属-半导体边界的金属态被视为反铁磁半金属，具有各向异性的斯莱特带隙。
Electrical resistivity (ρ) and Seebeck-coefficient measurements (α) are reported for Ni S 2− x Se x single crystals in the range 0<~ x<~ 0.71. There is a general trend toward increasing metallicity with increasing x. In the range 0.38<~ x<~ 0.51 a pronounced rise of ρ with temperature (T) is observed where the antiferromagnetic insulating (or antiferromagnetic metallic) phase changes over to the paramagnetic insulating phase. The analysis of α vs T curves suggests that in the low-temperature insulating state both holes and electrons participate in charge transport. It is emphasized that the many changes in electrical characteristics occur without significant alterations in the pyrite crystal structure, and that physical properties are greatly altered solely by adjustment of the anion sublattice while the cation sublattice remains intact. The results concerning electrical transport for the samples with 0.38<~ x<~ 0.55 are interpreted qualitatively on the basis of an onset of the Hubbard splitting into subbands at the transition to the insulating (semiconducting) state, which takes place in the temperature interval (50-100 K) upon heating the samples. The metallic state close to the metal-semiconductor boundary is viewed as being an antiferromagnetic semimetal, with an anisotropic Slater gap.