Blasco J, Sesé J, Rodríguez-Velamazán J A, Ritter C, Herrero-Martín J
Instituto de Ciencia de Materiales de Aragón, Departamento de Física de la Materia Condensada, CSIC-Universidad de Zaragoza, Pedro Cerbuna 12, E-50009 Zaragoza, Spain.
J Phys Condens Matter. 2009 May 27;21(21):216008. doi: 10.1088/0953-8984/21/21/216008. Epub 2009 May 1.
We have studied the Sr(2-x)La(x)Fe(1+x/2)Re(1-x/2)O(6) series in order to check how the increase in the number of Fe-O-Fe superexchange interactions affects the magnetic properties of this family of double perovskites. In these compounds the addition of La(3+) can be compensated by an increase of the Fe(3+) ratio leading to a non-electron-doped system. The unit cell of these samples expands on replacing Sr by La and the cationic ordering disappears for x>1 samples. Spontaneous magnetization at 5 K is observed in a wide range of concentrations but the magnetization at 5 T decreases as the La content increases. This result may be explained in terms of a ferrimagnetic ground state of the double perovskite. The magnetic ordering temperature increases with increasing the La and Fe content in agreement with an increase in the number of Fe-O-Fe interactions. The comparison to the electron-doped samples suggests that this effect is not enough to explain on its own the stronger T(C)-rise in Sr(2-x)La(x)FeReO(6) compounds.
我们研究了Sr(2-x)La(x)Fe(1+x/2)Re(1-x/2)O(6)系列，以检验Fe-O-Fe超交换相互作用数量的增加如何影响这类双钙钛矿的磁性能。在这些化合物中，La(3+)的添加可通过Fe(3+)比例的增加来补偿，从而形成非电子掺杂体系。这些样品的晶胞在La取代Sr时会膨胀，且对于x>1的样品，阳离子有序性消失。在很宽的浓度范围内都观察到了5K时的自发磁化，但5T时的磁化强度会随着La含量的增加而降低。这一结果可以用双钙钛矿的亚铁磁基态来解释。磁有序温度随着La和Fe含量的增加而升高，这与Fe-O-Fe相互作用数量的增加相一致。与电子掺杂样品的比较表明，这种效应不足以单独解释Sr(2-x)La(x)FeReO(6)化合物中更强的Tc上升现象。
