DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Roughness effects in uncompensated antiferromagnets

Abstract

Monte Carlo simulations show that roughness in uncompensated antiferromagnets decreases not just the surface magnetization but also the net magnetization and particularly strongly affects the temperature dependence. In films with step-type roughness, each step creates a new compensation front that decreases the global net magnetization. The saturation magnetization decreases non-monotonically with increasing roughness and does not scale with the surface area. Roughness in the form of surface vacancies changes the temperature-dependence of the magnetization; when only one surface has vacancies, the saturation magnetization will decrease linearly with surface occupancy, whereas when both surfaces have vacancies, the magnetization is negative and exhibits a compensation point at finite temperature, which can be tuned by controlling the occupancy. Roughness also affects the spin-texture of the surfaces due to long-range dipolar interactions and generates non-collinear spin configurations that could be used in devices to produce locally modified exchange bias. Lastly, these results explain the strongly reduced magnetization found in magnetometry experiments and furthers our understanding of the temperature-dependence of exchange bias.

Authors:
 [1];  [2]
  1. Univ. of California, Berkeley, CA (United States). Dept. of Physics; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Science Division; Federal Inst. of Technology, Zurich (Switzerland). Lab. of Metal Physics and Technology
  2. Univ. of California, Berkeley, CA (United States). Dept. of Physics; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Science Division
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1512172
Alternate Identifier(s):
OSTI ID: 1228199
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 117; Journal Issue: 8; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats

Charilaou, M., and Hellman, F. Roughness effects in uncompensated antiferromagnets. United States: N. p., 2015. Web. doi:10.1063/1.4913594.
Charilaou, M., & Hellman, F. Roughness effects in uncompensated antiferromagnets. United States. https://doi.org/10.1063/1.4913594
Charilaou, M., and Hellman, F. Wed . "Roughness effects in uncompensated antiferromagnets". United States. https://doi.org/10.1063/1.4913594. https://www.osti.gov/servlets/purl/1512172.
@article{osti_1512172,
title = {Roughness effects in uncompensated antiferromagnets},
author = {Charilaou, M. and Hellman, F.},
abstractNote = {Monte Carlo simulations show that roughness in uncompensated antiferromagnets decreases not just the surface magnetization but also the net magnetization and particularly strongly affects the temperature dependence. In films with step-type roughness, each step creates a new compensation front that decreases the global net magnetization. The saturation magnetization decreases non-monotonically with increasing roughness and does not scale with the surface area. Roughness in the form of surface vacancies changes the temperature-dependence of the magnetization; when only one surface has vacancies, the saturation magnetization will decrease linearly with surface occupancy, whereas when both surfaces have vacancies, the magnetization is negative and exhibits a compensation point at finite temperature, which can be tuned by controlling the occupancy. Roughness also affects the spin-texture of the surfaces due to long-range dipolar interactions and generates non-collinear spin configurations that could be used in devices to produce locally modified exchange bias. Lastly, these results explain the strongly reduced magnetization found in magnetometry experiments and furthers our understanding of the temperature-dependence of exchange bias.},
doi = {10.1063/1.4913594},
journal = {Journal of Applied Physics},
number = 8,
volume = 117,
place = {United States},
year = {Wed Feb 25 00:00:00 EST 2015},
month = {Wed Feb 25 00:00:00 EST 2015}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 19 works
Citation information provided by
Web of Science

Figures / Tables:

FIG. 1 FIG. 1: Thin antiferromagnets in the N eel state with and without steps. Spins in the same atomic plane point in the same direction, indicated by the arrows, such that the magnetization of each plane is antiparallel to that of the adjacent planes. The top film a shows a perfectmore » uncompensated flat antiferromagnet with 5 atomic planes. Panel (b) shows an uncompensated AFM with 5 atomic planes, and six conformal steps (7 plateaus), where the net magnetization is equal to 1/7. Panel (c) shows an AFM with flat bottom atomic plane and rough top surface with thicker and thinner areas; here the net magnetization is equal to 4/7. While these examples show systems where the change in thickness is monotonic, the results apply to non-monotonic varying thickness as well, i.e., when some steps go up and some steps go down. The length of each arrow in each atomic plane indicates how the magnetic moment at the surface is weaker at finite temperature.« less

Save / Share:

Works referenced in this record:

Pinned magnetization in the antiferromagnet and ferromagnet of an exchange bias system
journal, June 2007


Microscopic model for exchange anisotropy
journal, February 2002


Robust isothermal electric control of exchange bias at room temperature
journal, June 2010

  • He, Xi; Wang, Yi; Wu, Ning
  • Nature Materials, Vol. 9, Issue 7
  • DOI: 10.1038/nmat2785

Self‐consistent domain theory in soft‐ferromagnetic media. II. Basic domain structures in thin‐film objects
journal, August 1986

  • van den Berg, H. A. M.
  • Journal of Applied Physics, Vol. 60, Issue 3
  • DOI: 10.1063/1.337352

Spintronics: A Spin-Based Electronics Vision for the Future
journal, November 2001

  • Wolf, S. A.; Awschalom, D. D.; Buhrman, R. A.
  • Science, Vol. 294, Issue 5546, p. 1488-1495
  • DOI: 10.1126/science.1065389

Heisenberg-to-Ising crossover in a random-field model with uniaxial anisotropy
journal, May 1988


Dipolar effects in multilayers with interface roughness
journal, September 2000


Exchange anisotropy — a review
journal, October 1999


Mean-field simulation of metal oxide antiferromagnetic films and multilayers
journal, May 2013


Electron-Mediated Ferromagnetic Behavior in CoO / ZnO Multilayers
journal, February 2013


Anisotropie magnétique superficielle et surstructures d'orientation
journal, January 1954


Crystalline and magnetic anisotropy of the 3 d -transition metal monoxides MnO, FeO, CoO, and NiO
journal, September 2012


Exchange bias in nanostructures
journal, December 2005


Fast Monte Carlo method for magnetic nanoparticles
journal, March 2006


Direct Measurement of Rotatable and Frozen CoO Spins in Exchange Bias System of CoO / Fe / Ag ( 001 )
journal, May 2010


Exchange bias of the interface spin system at the Fe/MgO interface
journal, June 2013


Depth Profile of Uncompensated Spins in an Exchange Bias System
journal, July 2005


Giant Magnetoresistance of (001)Fe/(001)Cr Magnetic Superlattices
journal, November 1988


Mechanism of magnetization enhancement at CoO/permalloy interfaces
journal, August 2013

  • Grytsyuk, Sergiy; Schwingenschlögl, Udo
  • Applied Physics Letters, Vol. 103, Issue 7
  • DOI: 10.1063/1.4818507

Domain state model for exchange bias. I. Theory
journal, July 2002


Magnetoelectronics
journal, November 1998


Tuning the magnetic coupling across ultrathin antiferromagnetic films by controlling atomic-scale roughness
journal, January 2006

  • Kuch, W.; Chelaru, L. I.; Offi, F.
  • Nature Materials, Vol. 5, Issue 2
  • DOI: 10.1038/nmat1548

Exchange bias
journal, February 1999


Simple model for thin ferromagnetic films exchange coupled to an antiferromagnetic substrate
journal, October 1987

  • Mauri, D.; Siegmann, H. C.; Bagus, P. S.
  • Journal of Applied Physics, Vol. 62, Issue 7
  • DOI: 10.1063/1.339367

Interface reaction of NiO/NiFe and its influence on magnetic properties
journal, March 2001

  • Yu, G. H.; Chai, C. L.; Zhu, F. W.
  • Applied Physics Letters, Vol. 78, Issue 12
  • DOI: 10.1063/1.1343474

Anomalous magnetic thermodynamics in uncompensated collinear antiferromagnets
journal, July 2014


Surface-induced phenomena in uncompensated collinear antiferromagnets
journal, February 2015


Mechanisms for exchange bias
journal, November 2000


Generic source of perpendicular anisotropy in amorphous rare-earth–transition-metal films
journal, February 1991


Increased exchange anisotropy due to disorder at permalloy/CoO interfaces
journal, August 1995

  • Moran, T. J.; Gallego, J. M.; Schuller, Ivan K.
  • Journal of Applied Physics, Vol. 78, Issue 3
  • DOI: 10.1063/1.360225

Measurement of Spin-Wave Dispersion in NiO by Inelastic Neutron Scattering and Its Relation to Magnetic Properties
journal, November 1972


Uncompensated Moments in the MnPd / Fe Exchange Bias System
journal, September 2008


Finite size effects on the moment and ordering temperature in antiferromagnetic CoO layers
journal, February 2003


Exchange-biased magnetic tunnel junctions and application to nonvolatile magnetic random access memory (invited)
journal, April 1999

  • Parkin, S. S. P.; Roche, K. P.; Samant, M. G.
  • Journal of Applied Physics, Vol. 85, Issue 8
  • DOI: 10.1063/1.369932

Random-field model of exchange anisotropy at rough ferromagnetic-antiferromagnetic interfaces
journal, March 1987


An ab initio cluster study of the magnetic properties of the CoO(001) surface
journal, May 2002


Evidence of modified ferromagnetism at a buried Permalloy/CoO interface at room temperature
journal, January 2007


Mechanisms of exchange anisotropy (invited)
journal, April 1988

  • Malozemoff, A. P.
  • Journal of Applied Physics, Vol. 63, Issue 8
  • DOI: 10.1063/1.340591

Scaling Approach to the Magnetic Phase Diagram of Nanosized Systems
journal, May 2002


Works referencing / citing this record:

Magnetocaloric effect in cubically anisotropic magnets
journal, January 2019

  • Hu, Yong; Hu, Tianyi; Chi, Xiaodan
  • Applied Physics Letters, Vol. 114, Issue 2
  • DOI: 10.1063/1.5081130

Influence of atomic roughness at the uncompensated Fe/CoO(111) interface on the exchange-bias effect
journal, January 2020


Imaging uncompensated moments and exchange-biased emergent ferromagnetism in FeRh thin films
journal, December 2019


Influence of atomic roughness at the uncompensated Fe/CoO(111) interface on the exchange-bias effect
text, January 2020

  • Wu, R.; Xue, M.; Maity, T.
  • Apollo - University of Cambridge Repository
  • DOI: 10.17863/cam.48044

Imaging uncompensated moments and exchange-biased emergent ferromagnetism in FeRh thin films
text, January 2019


Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.