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Copper-Substituted Iron Telluride: A Phase Diagram



Patrick N. Valdivia, Min Gyu Kim, Thomas R. Forrest, Zhijun Xu, Meng Wang, Hui Wu, Leland Harriger, Edith D. Bourret-Courchesne, Robert J. Birgeneau


Metal site alloying of the iron chalcogenides is known to give rise to bulk insulating states with no known analogue in the iron arsenide phase diagrams. We have studied the structure, magnetic, and transport properties of copper substituted iron telluride. Our results extend the range of copper substitution to 60% substitution per formula unit, which is far beyond previously assumed solubility limits. Substitution of copper into antiferromagnetic iron telluride is found to suppress the signatures of the low-temperature transitions in susceptibility and resistance measurements, giving rise to a bulk insulating , spin glass ground state. Upon increasing the cooper substitution from 4% to 6%, short range magnetic correlations appear, which presage the combined magnetic and structural transition at a lower temperature, although the magnetic order is ultimately resolution limited with a correlation length of 25 nm in the 6% Cu-substituted sample, in contrast to the magnetic order of the 4% copper substituted sample, which is resolution limited. Upon warming the 6% Cu-substituted sample in the presence of a 5T magnetic field oriented along the b-axis, a magnetic and structural phase transition is observed at a temperature much lower than those of the magnetic and structural transitions which occur in zero field. Furthermore, these transitions are absent upon cooling in this field. We discuss these latter observations in terms of a magnetostructural transition in which the field detwins the sample, and also discuss potential random field effects.
Physical Review B


Superconductivity, Chalcogenides, Magnetism, Phase Diagram


Valdivia, P. , Kim, M. , Forrest, T. , Xu, Z. , Wang, M. , Wu, H. , Harriger, L. , Bourret-Courchesne, E. and Birgeneau, R. (2015), Copper-Substituted Iron Telluride: A Phase Diagram, Physical Review B, [online], (Accessed July 25, 2024)


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Created June 21, 2015, Updated October 12, 2021