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Disorder-induced time effect in the antiferromagnetic domain state of Fe1+yTe

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  • Jan Fikáček, Czech Academy of Sciences
  • ,
  • Jonas Warmuth, University of Hamburg
  • ,
  • Fabian Arnold
  • ,
  • Cinthia Piamonteze, Paul Scherrer Institute
  • ,
  • Zhiqiang Mao, Eberly College of Science
  • ,
  • Václav Holý, Charles University
  • ,
  • Philip Hofmann
  • Martin Bremholm
  • Jens Wiebe, University of Hamburg
  • ,
  • Roland Wiesendanger, University of Hamburg
  • ,
  • Jan Honolka, Czech Academy of Sciences

We report on temperature-dependent soft X-ray absorption spectroscopy (XAS) measurements utilizing linearly polarized synchrotron radiation to probe magnetic phase transitions in iron-rich Fe1+yTe (y ≈ 0.12). X-ray magnetic linear dichroism (XMLD) signals, which sense magnetic ordering processes at surfaces, start to increase monotonically below the Néel temperature TN = 57 K. This increase is due to a progressive bicollinear antiferromagnetic (AFM) alignment of Fe spins of the monoclinic Fe1+yTe parent phase. This AFM alignment was achieved by a [1 0 0]-oriented biasing field favoring a single-domain state during cooling across TN. Our specific heat and magnetization measurements confirm the bulk character of this AFM phase transition. On longer time scales, however, we observe that the field-biased AFM state is highly unstable even at the lowest temperature of T = 3 K. After switching off the biasing field, the XMLD signal decays exponentially with a time constant τ = 1506 s. The initial XMLD signal is restored only upon repeating a cycle consisting of heating and field-cooling through TN. We explain the time effect by a gradual formation of a multi-domain state with 90° rotated AFM domains, promoted by structural disorder, facilitating the motion of twin-domains. Significant disorder in our Fe1+yTe sample is evident from our X-ray diffraction and specific heat data. The stability of magnetic phases in Fe-chalcogenides is an important material property, since the Fe(Te1-xSex) phase diagram shows magnetism intimately connected with superconductivity.

TidsskriftJournal of Magnetism and Magnetic Materials
StatusUdgivet - dec. 2021

Bibliografisk note

Funding Information:
The authors express their highest gratitude to Dr. Sahana Rößler for very helpful discussions. This work was supported by the Czech Science Foundation Grant No. 19-13659S. We acknowledge support by the European CALIPSOplus program for experiments at the Swiss Light Source. This work was supported by the DFG via the priority program SPP1666 (grant nos. HO 5150/1-2 and WI 3097/2-2). Martin Bremholm and Philip Hofmann acknowledge the Villum Centre of Excellence for Dirac Materials (Grant No.11744), and Martin Bremholm furthermore the Danish Council for Independent Research under the Sapere Aude program (Grant No. 7027-00077B). Zhiqiang Mao acknowledges the support from the US Department of Energy under grant DE-SC0019068.

Publisher Copyright:
© 2021 Elsevier B.V.

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