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Anisotropic magnetic order of the Eu sublattice in single crystals of EuFe_{2−x}Co_{x}As_{2} (x=0,0.2) studied by means of magnetization and magnetic torque


Guguchia, Z; Bosma, S; Weyeneth, S; Shengelaya, A; Puzniak, R; Bukowski, Z; Karpinski, J; Keller, H (2011). Anisotropic magnetic order of the Eu sublattice in single crystals of EuFe_{2−x}Co_{x}As_{2} (x=0,0.2) studied by means of magnetization and magnetic torque. Physical Review. B, Condensed Matter and Materials Physics, 84(14):144506.

Abstract

We present a combination of magnetization and magnetic torque experiments to investigate the magnetic orders in undoped EuFe2As2 and Co-doped EuFe1.8Co0.2As2 single crystals. Although at low temperatures typical results for an antiferromagnetic (AFM) state in EuFe2As2 were found, our data strongly indicate the occurrence of a canted antiferromagnetic (C-AFM) order of the Eu2+ moments between 17 and 19 K, observed even in the lowest studied magnetic fields. However, unlike in the parent compound, no low-field and low-temperature AFM state of the Eu2+ moments was observed in the doped EuFe1.8Co0.2As2. Only a C-AFM phase is present at low fields and low temperatures, with a reduced magnetic anisotropy as compared to the undoped system. We discuss for both EuFe2As2 and EuFe1.8Co0.2As2 the experimentally deduced magnetic phase diagrams of the magnetic ordering of the Eu2+ sublattice with respect to the temperature, the applied magnetic field, and its orientation to the crystallographic axes. It is likely that the magnetic coupling of the Eu and the Fe sublattice is strongly dependent on Co doping, having detrimental influence on the magnetic phase diagrams as determined in this work. Their impact on the occurrence of superconductivity with higher Co doping is discussed.

Abstract

We present a combination of magnetization and magnetic torque experiments to investigate the magnetic orders in undoped EuFe2As2 and Co-doped EuFe1.8Co0.2As2 single crystals. Although at low temperatures typical results for an antiferromagnetic (AFM) state in EuFe2As2 were found, our data strongly indicate the occurrence of a canted antiferromagnetic (C-AFM) order of the Eu2+ moments between 17 and 19 K, observed even in the lowest studied magnetic fields. However, unlike in the parent compound, no low-field and low-temperature AFM state of the Eu2+ moments was observed in the doped EuFe1.8Co0.2As2. Only a C-AFM phase is present at low fields and low temperatures, with a reduced magnetic anisotropy as compared to the undoped system. We discuss for both EuFe2As2 and EuFe1.8Co0.2As2 the experimentally deduced magnetic phase diagrams of the magnetic ordering of the Eu2+ sublattice with respect to the temperature, the applied magnetic field, and its orientation to the crystallographic axes. It is likely that the magnetic coupling of the Eu and the Fe sublattice is strongly dependent on Co doping, having detrimental influence on the magnetic phase diagrams as determined in this work. Their impact on the occurrence of superconductivity with higher Co doping is discussed.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Physics Institute
Dewey Decimal Classification:530 Physics
Language:English
Date:2011
Deposited On:14 Nov 2011 11:52
Last Modified:07 Dec 2017 09:37
Publisher:American Physical Society
ISSN:1098-0121
Publisher DOI:https://doi.org/10.1103/PhysRevB.84.144506
Related URLs:http://arxiv.org/abs/1107.2103

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