28 August 2022 to 2 September 2022
Science and Technology Campus, University of Parma
Europe/Rome timezone
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A MaxEnt-μSR study: Precursor effects of the Fe3O4 Verwey transition

P-THU-16
1 Sept 2022, 17:20
1h 40m
Science and Technology Campus, University of Parma

Science and Technology Campus, University of Parma

University of Parma, Italy
Poster Strongly correlated electron systems Posters

Speaker

Prof. Carolus Boekema (San Jose State University)

Description

Using muon-spin rotation (μSR) [1] the magnetic fields of Fe3O4 have been previously investigated. The Verwey transition at Tv (~123 K) and a transition at Tw (~247 K) are observed. Using Maximum-Entropy (MaxEnt) μSR data of single-crystal Fe3O4 are analyzed with much improved precision. [2,3] We review earlier results [3] and report on our analysis of the temperature dependence of fields with B (720 Oe) // <110>. Below the demagnetization field, extra μSR signals are found at Bext // <110> indicating two frequencies at room temperature (RT) and two at 205 K. [3] At RT, the upper frequency follows the zero-field trend seen in the Tv-Tw region of the zero-field (ZF) phase diagram. At 205 K, the lower frequency follows the extension of the ZF trend above Tw. These two ZF trends indicate plausible short-range ordering related to the “extra” 3d-electron conduction behavior. This should further be interpreted as precursor effects to the Tv transition. [1] Our MaxEnt-μSR finding is consistent with diffuse [4] & x-ray [5] scattering results above Tv providing a clear picture of the magnetic environments in Fe3O4. This new interpretation indicates two T-dependent magnetizations, reflecting different short-range orders [3-5] in the ZF phase diagram of this Mott-Wigner glass.[6]
Research supported by LANL-DOE, SJSU & AFC San Jose.
[1] C. Boekema et al, Phys Rev B33 (1986) 2102; Phys Rev B31 (1985) 1233 & references therein.
[2] C Boekema and MC Browne, MaxEnt 2008, AIP Conf Proc #1073 (2008) 260.
[3] C Morante and C Boekema, AIP Advances 10 (2020).025005.
[4] A Bosak et al, Phys Rev X4 (2014) 011040.
[5] G Perversi et al, Nature Comm 10 (2019).2857.
[6] JHVJ Brabers et al, J Physics Condensed Matter 12 (2000) 5437.

Primary authors

Prof. Carolus Boekema (San Jose State University) Carlos Morante (San Jose State University) Gautam Anand (San Jose State University)

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