Influence of covalency and anion polarization on magnetic and electronic properties of ZnCr_{2鈭?span style='font-style: italic'>x}Ni_xSe₄

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• 作者：Izabela Jendrzejewska^a ; ^izajen@wp.pl ; Paweł ; Zajdel^b ; Tomasz Goryczka^c ; Jerzy Goraus^b ; Andrzej Kita^a ; Tadeusz Mydlarz^d
• 关键词：Magnetically ordered materials ; X-ray diffraction ; Neutron diffraction ; Magnetic measurements ; EXAFS ; Electronic band structure
• 刊名：Journal of Alloys and Compounds
• 出版年：2012
• 期刊代码：45_09258388
• 类别：ms
• 出版时间：15 April, 2012
• 卷：520
• 期：Complete
• 页码：153-157
• 文件大小：689 K

摘要

Selenospinels ACr₂Se₄ form a broad class of materials with tunable properties, including thermoelectric, magnetoresistive and magnetocapacitance, related to the internal competing interactions.

On the basis of structural, magnetic and numerical studies of the cubic ZnCr_2鈭?em>xNi_xSe₄ (x = 0.1-0.3), we show that simple ionic model is not suitable for consistent description of the properties of the system. Although it may explain the systematic decrease of the saturation magnetic moments from 5.25渭_B/f.u. for x = 0.1 to 4.85渭_B/f.u. for x = 0.3, it fails to explain the trends in the lattice parameters and the chemical shifts of the absorption edges.

On the basis of the numerical calculations performed for x = 0.2, we obtain the agreement between the local magnetic moments on Cr (3.18渭_B) and Ni (鈭?.49渭_B) ions and the value obtained from neutron powder diffraction 2.65(3)渭_B as well as saturation magnetization. However, the calculations and the consistence between different experiments require the presence of magnetic polarization on selenium 鈭?.11渭_B, which is usually neglected in ionic models.