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首页> 外文期刊>Journal of Experimental and Theoretical Physics >Phase transformations and magnetotransport properties of the Pr _(0.5)Sr_(0.5)Co_(1-x)Mn_xO_3 system
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Phase transformations and magnetotransport properties of the Pr _(0.5)Sr_(0.5)Co_(1-x)Mn_xO_3 system

机译：Pr _（0.5）Sr_（0.5）Co_（1-x）Mn_xO_3系统的相变和磁输运性质

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摘要

The structural, magnetic, and magnetotransport properties of Pr _(0.5)Sr_(0.5)Co_(1 - x)Mn_xO_3 (x < 0.65) perovskites are studied by magnetization and electrical conductivity measurements in magnetic fields up to 14 T and by neutron diffraction. In the manganese concentration range x < 0.5 and T = 300 K, the crystal structure is described by monoclinic space group I2/a; at x > 0.5, it is described by orthorhombic space group Imma. When the temperature decreases, a structural transformation without changing the symmetry takes place in all compounds. This transformation is caused by an active role of the inner shells of the praseodymium ion in chemical bond formation. The substitution of manganese for cobalt breaks a long-range ferromagnetic order near x ≈ 0.25, and a metal-dielectric transition occurs at x ≈ 0.15. The negative magnetoresistance is found to be maximal near a critical manganese concentration, where a long-range magnetic order is broken; it reaches 95% in a field of 14 T at T = 10 K for x = 0.2. An unusual dielectric magnetic state with a small spontaneous magnetic moment and a sharp transition into a paramagnetic state at T > 200 K is revealed in the concentration range 0.30 ≤ x ≤ 0.65 in spite of the absence of coherent magnetic neutron scattering. A model is proposed to explain the behavior of the magnetic properties in this phase.
机译：通过在高达14 T的磁场中进行磁化和电导率测量并通过中子衍射研究了Pr _（0.5）Sr_（0.5）Co_（1-x）Mn_xO_3（x <0.65）钙钛矿的结构，磁性和磁传输性质。在锰浓度范围x <0.5且T = 300 K时，晶体结构由单斜晶空间群I2 / a描述;当x> 0.5时，由正交空间群Imma描述。当温度降低时，所有化合物都发生结构变化而不改变对称性。这种转变是由ody离子内壳在化学键形成中的积极作用引起的。锰替代钴破坏了x≈0.25附近的远距离铁磁有序，并且金属介电跃迁发生在x≈0.15。发现负磁阻在临界锰浓度附近最大，在锰浓度下，远距离磁序被破坏。在x = 0.2的T = 10 K的情况下，它在14 T的场中达到95％。尽管没有相干磁中子散射，但在0.30≤x≤0.65的浓度范围内，仍显示出具有异常的介电磁态，该介电磁态具有较小的自发磁矩并且在T> 200 K时会急剧转变为顺磁态。提出了一个模型来解释此阶段的磁性能。

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