High Magnetic Field Study on Giant Negative Magnetoresistance in the Molecular Conductor TPP[Cr(Pc)(CN)2]2
High Magnetic Field Study on Giant Negative Magnetoresistance in the Molecular Conductor TPP[Cr(Pc)(CN)2]2
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DOI：
10.7566/jpsj.85.064713
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发表时间：
2016-06-15
影响因子：
1.7
通讯作者：
Hanasaki, Noriaki
中科院分区：
文献类型：
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作者：
Ikeda, Mitsuo;Kida, Takanori;Hanasaki, Noriaki
我们研究了酞菁分子导体TPP[Cr(Pc)(CN)(2)](2)在高达54T的磁场中的磁性和输运性质。由于电子自旋共振测量证实了各向同性，我们观察到了几乎不依赖于磁场方向的巨大负磁电阻。磁阻的大小[垂直杆Rho(µH-0)/Rho(0T)-1垂直杆]与自旋散射过程中观察到的磁化强度的平方成正比，而比例系数随着温度的降低而增加。磁化强度即使在53T也不饱和，表明局域自旋之间存在较大的反铁磁交换相互作用。尽管存在这种反铁磁交换作用和低维，但在低温和高磁场范围内观察到了凸磁化曲线。为了再现这一磁化曲线，我们提出了一个考虑相邻π电子自旋之间的反铁磁交换相互作用的模型。
We investigated the magnetic and transport properties of the phthalocyanine molecular conductor TPP[Cr(Pc)(CN)(2)](2) in magnetic fields of up to 54 T. We observed giant negative magnetoresistance which hardly depends on the magnetic field direction owing to the isotropic nature confirmed by electron spin resonance measurements. The magnitude of magnetoresistance [vertical bar rho(mu H-0)/rho(0T) -1 vertical bar] is proportional to the square of magnetization as observed in the case of the spin scattering process, while the proportionality coefficient increases with decreasing the temperature. The magnetization does not saturate even at 53 T, indicating the existence of the large antiferromagnetic exchange interactions between the localized spins. In spite of this antiferromagnetic exchange interaction and low dimensionality, a convex magnetization curve was observed in the low temperature and high magnetic field range. To reproduce this magnetization curve, we proposed a model taking into account the antiferromagnetic exchange interaction between the neighboring pi-electron spins.