Response of the Verwey transition in magnetite to controlled point-like disorder induced by 2.5 MeV electron irradiation
Journal Article
·
· Materials Research Bulletin
- Ames Laboratory (AMES), Ames, IA (United States); Iowa State University, Ames, IA (United States)
- Ecole Polytechnique, Palaiseau (France). Centre National de la Recherche Scientifique (CNRS)
Controlled point-like disorder induced by low temperature 2.5 MeV electron irradiation was used to probe the nature of the Verwey transition in magnetite, Fe3O4. Two large single crystals, one with optimal transition temperature, TV ≈ 121 K, and another with TV ≈ 109 K, as well as magnetite magnetosome nanocrystals harvested from the lysed cells of the marine magnetotactic vibrio Magnetovibrio blakemorei strain MV-1, TV ≈ 110 K, were examined. Temperature-dependent resistivity is consistent with the semiconductor-to-semiconductor (insulator) sharp, step-like Verwey transition from a state with a small bandgap of around 60 meV to a state with a large bandgap of about 300 meV. The irradiation causes an up-shift of the resistivity curves above the transition without transition smearing or broadening. It also causes an apparent down-shift of the resistivity maximum at high temperatures. In the lower crystal, the electron irradiation drives the transition temperature into a “forbidden” interval of TV , believed to separate the first order from the second order phase transition. Contrary to this belief, the transition itself remains sharp and hysteretic without a significant change in the hysteresis width indicating the strong 1st order character of the Verwey transition for all TV values. The separate 2nd order - looking transition is likely due to sample inhomogeneities. Here we conclude that the sudden change of the bandgap accompanied (or driven) by the monoclinic distortion and the change of magnetic anisotropy is the reason for the Verwey transition in magnetite and the effect of additional disorder is mostly in the smearing of the sharp gap edges near the Fermi level.
- Research Organization:
- Ames Laboratory (AMES), Ames, IA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE)
- Grant/Contract Number:
- AC02-07CH11358
- OSTI ID:
- 1993989
- Report Number(s):
- IS-J -11,118
- Journal Information:
- Materials Research Bulletin, Journal Name: Materials Research Bulletin Vol. 167; ISSN 0025-5408
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
Charge-Orbital Ordering and Verwey Transition in Magnetite Measured by Resonant Soft X-Ray Scattering
Verwey transition in magnetite
Single-particle gap above the Verwey transition in Fe{sub 3}O{sub 4}
Journal Article
·
Thu Mar 09 23:00:00 EST 2006
· Physical Review Letters
·
OSTI ID:20778771
Verwey transition in magnetite
Conference
·
Fri Dec 31 23:00:00 EST 1976
·
OSTI ID:7316371
Single-particle gap above the Verwey transition in Fe{sub 3}O{sub 4}
Journal Article
·
Thu May 01 00:00:00 EDT 1997
· Physical Review, B: Condensed Matter
·
OSTI ID:565333