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arXiv · 0808.2247

Magnetic phase diagram in Eu$_{1-x}$La$_x$Fe$_2$As$_2$ single crystals

T. Wu·G. Wu·H. Chen·Y. L. Xie·R. H. Liu·X. F. Wang·X. H. Chen
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Abstract

We have systematically measured resistivity, susceptibility and specific heat under different magnetic fields (H) in Eu$_{1-x}$La$_x$Fe$_2$As$_2$ single crystals. It is found that a metamagnetic transition from A-type antiferromagnetism to ferromagnetism occurs at a critical field for magnetic sublattice of $Eu^{2+}$. The jump of specific heat is suppressed and shifts to low temperature with increasing H up to the critical value, then shifts to high temperature with further increasing H. Such behavior supports the metamagnetic transition. Detailed H-T phase diagrams for x=0 and 0.15 crystals are given, and possible magnetic structure is proposed. Magnetoresistance measurements indicate that there exists a strong coupling between local moment of $Eu^{2+}$ and charge in Fe-As layer. These results are very significant to understand the underlying physics of FeAs superconductors.

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T. Wu, G. Wu, H. Chen, Y. L. Xie, R. H. Liu, X. F. Wang, X. H. Chen. 2008-08-16. Magnetic phase diagram in Eu$_{1-x}$La$_x$Fe$_2$As$_2$ single crystals. https://doi.org/10.1016/j.jmmm.2009.07.043

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