Magnetism of insulator phase in SrRu1−xMnxO3 (0.4⩽x⩽0.6)
Introduction
In the strongly correlated electron systems, the perovskite SrRuO3 is well known to be itinerant ferromagnetic compound with the Curie temperature ∼160 K and the ordered moment of ∼1.1 μB [1], [2]. The Ru 4d electrons play important roles in the magnetic and transport properties with nature of strong correlation and itinerant-localized duality. While the cubic perovskite SrMnO3 is reported to be anti-ferromagnet with the Néel temperature TN=260 K [3]. We have measured magnetic and transport properties of SrRu1−xMnxO3 (0.4⩽x⩽0.6) solid solutions to make clear the magnetism from itinerant ferromagnet to localized anti-ferromagnet through the Mn substitution [4]. The Mn doping gives rise to a metal–insulator transition around x=0.25, and the magnetic phase transition from ferromagnetic state to anti-ferromagnetic state. From powder neutron diffraction measurements on this system, we found that the itinerant ferromagnetic order observed in pure SrRuO3 changes into the C-type anti-ferromagnetic (AF) order with nearly localized d electrons in the intermediate Mn concentration range between x=0.4 and 0.6 [5]. In the study of magnetic properties, we find that the susceptibility peak does not agree with the Néel temperature determined from the neutron diffraction. In this paper, we report the results of magnetization measurement in the insulator phase at high magnetic fields and discuss the difference of magnetic peak between in high and low magnetic fields.
Section snippets
Experiment
Polycrystalline samples of SrRu1−xMnxO3 (0.4⩽x⩽0.6) were synthesized by the solid-state-reaction method. After pre-sintering, we repeated sintering and grinding 10 times in the air atmosphere at 1300 °C for 24 h. The crystal structure of SrRu1−xMnxO3 (0.4⩽x⩽0.6) was tetragonal structure with space group I4/mcm.
The magnetic measurement was carried out by extraction method with 15 T superconducting magnet in the range of 5–300 K.
Results and discussion
Fig. 1 shows the temperature dependence of magnetization measured in the insulator phase on Mn concentration x=0.6 at high magnetic fields. The peak of magnetization changes from 210 to 250 K with increasing magnetic field up to 5 T (Fig. 2). The Néel temperature obtained from the neutron diffraction experiment agrees with the peak temperature TP measured in high magnetic fields. However, TP observed in the low magnetic field, is much lower than the anti-ferromagnetism transition temperature TN.
Conclusion
We performed magnetization measurement in insulator phase on SrRu1−xMnxO3 (0.4⩽x⩽0.6) at high magnetic fields up to 15 T. As a result the peak temperature of magnetization TP changes from 210 in low magnetic field to 250 K in high magnetic field for the sample with x=0.6. The Néel temperature obtained from the neutron diffraction experiment agrees with the peak temperature TP measured in high magnetic fields. However, TP observed in the low magnetic field, is much lower than anti-ferromagnetic
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Cited by (1)
Augmentation of coercivity in nanocrystalline SrRuO<inf>3</inf> thin film and its spin glass behavior
2015, Journal of Magnetism and Magnetic MaterialsCitation Excerpt :The effect of iron substitution and epitaxial strain is widely studied lately as well. For example, accompanying with the structural variation, both the electric and magnetic properties varied by substituting Ca for Sr [12,13], or substituting Mn or Cr for Ru [14,15]. Moreover, it is recently reported that magnetization can be greatly enhanced in SrRuO3 films through lattice distortions generated by epitaxial strain [16].