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Title: Discovery of intrinsic ferromagnetism in two-dimensional van der Waals crystals

Abstract

The realization of long-range ferromagnetic order in two-dimensional van der Waals crystals, combined with their rich electronic and optical properties, could lead to new magnetic, magnetoelectric and magneto-optic applications1,2,3,4. In two-dimensional systems, the long-range magnetic order is strongly suppressed by thermal fluctuations, according to the Mermin–Wagner theorem5; however, these thermal fluctuations can be counteracted by magnetic anisotropy. Previous efforts, based on defect and composition engineering6,7,8,9,10, or the proximity effect, introduced magnetic responses only locally or extrinsically. Here we report intrinsic long-range ferromagnetic order in pristine Cr2Ge2Te6 atomic layers, as revealed by scanning magneto-optic Kerr microscopy. In this magnetically soft, two-dimensional van der Waals ferromagnet, we achieve unprecedented control of the transition temperature (between ferromagnetic and paramagnetic states) using very small fields (smaller than 0.3 tesla). This result is in contrast to the insensitivity of the transition temperature to magnetic fields in the three-dimensional regime. We found that the small applied field leads to an effective anisotropy that is much greater than the near-zero magnetocrystalline anisotropy, opening up a large spin-wave excitation gap. We explain the observed phenomenon using renormalized spin-wave theory and conclude that the unusual field dependence of the transition temperature is a hallmark of soft, two-dimensional ferromagnetic vanmore » der Waals crystals. Cr2Ge2Te6 is a nearly ideal two-dimensional Heisenberg ferromagnet and so will be useful for studying fundamental spin behaviours, opening the door to exploring new applications such as ultra-compact spintronics.« less

Authors:
 [1];  [2];  [3];  [4];  [2];  [1];  [3];  [1];  [1];  [5];  [6];  [4];  [3];  [2];  [5]
  1. Univ. of California, Berkeley, CA (United States). Nano-scale Science and Engineering Center (NSEC)
  2. Univ. of California, Irvine, CA (United States). Dept. of Physics and Astronomy
  3. Univ. of California, Berkeley, CA (United States). Dept. of Physics; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division
  4. Princeton Univ., NJ (United States). Dept. of Chemistry
  5. Univ. of California, Berkeley, CA (United States). Nano-scale Science and Engineering Center (NSEC); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division
  6. Univ. of California, Berkeley, CA (United States). Dept. of Physics
Publication Date:
Research Org.:
Lawrence Berkeley National Laboratory-National Energy Research Scientific Computing Center
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
OSTI Identifier:
1489264
DOE Contract Number:  
AC02-05CH11231
Resource Type:
Journal Article
Journal Name:
Nature (London)
Additional Journal Information:
Journal Volume: 546; Journal Issue: 7657; Journal ID: ISSN 0028-0836
Country of Publication:
United States
Language:
English

Citation Formats

Gong, Cheng, Li, Lin, Li, Zhenglu, Ji, Huiwen, Stern, Alex, Xia, Yang, Cao, Ting, Bao, Wei, Wang, Chenzhe, Wang, Yuan, Qiu, Z. Q., Cava, R. J., Louie, Steven G., Xia, Jing, and Zhang, Xiang. Discovery of intrinsic ferromagnetism in two-dimensional van der Waals crystals. United States: N. p., 2017. Web. doi:10.1038/nature22060.
Gong, Cheng, Li, Lin, Li, Zhenglu, Ji, Huiwen, Stern, Alex, Xia, Yang, Cao, Ting, Bao, Wei, Wang, Chenzhe, Wang, Yuan, Qiu, Z. Q., Cava, R. J., Louie, Steven G., Xia, Jing, & Zhang, Xiang. Discovery of intrinsic ferromagnetism in two-dimensional van der Waals crystals. United States. doi:10.1038/nature22060.
Gong, Cheng, Li, Lin, Li, Zhenglu, Ji, Huiwen, Stern, Alex, Xia, Yang, Cao, Ting, Bao, Wei, Wang, Chenzhe, Wang, Yuan, Qiu, Z. Q., Cava, R. J., Louie, Steven G., Xia, Jing, and Zhang, Xiang. Wed . "Discovery of intrinsic ferromagnetism in two-dimensional van der Waals crystals". United States. doi:10.1038/nature22060.
@article{osti_1489264,
title = {Discovery of intrinsic ferromagnetism in two-dimensional van der Waals crystals},
author = {Gong, Cheng and Li, Lin and Li, Zhenglu and Ji, Huiwen and Stern, Alex and Xia, Yang and Cao, Ting and Bao, Wei and Wang, Chenzhe and Wang, Yuan and Qiu, Z. Q. and Cava, R. J. and Louie, Steven G. and Xia, Jing and Zhang, Xiang},
abstractNote = {The realization of long-range ferromagnetic order in two-dimensional van der Waals crystals, combined with their rich electronic and optical properties, could lead to new magnetic, magnetoelectric and magneto-optic applications1,2,3,4. In two-dimensional systems, the long-range magnetic order is strongly suppressed by thermal fluctuations, according to the Mermin–Wagner theorem5; however, these thermal fluctuations can be counteracted by magnetic anisotropy. Previous efforts, based on defect and composition engineering6,7,8,9,10, or the proximity effect, introduced magnetic responses only locally or extrinsically. Here we report intrinsic long-range ferromagnetic order in pristine Cr2Ge2Te6 atomic layers, as revealed by scanning magneto-optic Kerr microscopy. In this magnetically soft, two-dimensional van der Waals ferromagnet, we achieve unprecedented control of the transition temperature (between ferromagnetic and paramagnetic states) using very small fields (smaller than 0.3 tesla). This result is in contrast to the insensitivity of the transition temperature to magnetic fields in the three-dimensional regime. We found that the small applied field leads to an effective anisotropy that is much greater than the near-zero magnetocrystalline anisotropy, opening up a large spin-wave excitation gap. We explain the observed phenomenon using renormalized spin-wave theory and conclude that the unusual field dependence of the transition temperature is a hallmark of soft, two-dimensional ferromagnetic van der Waals crystals. Cr2Ge2Te6 is a nearly ideal two-dimensional Heisenberg ferromagnet and so will be useful for studying fundamental spin behaviours, opening the door to exploring new applications such as ultra-compact spintronics.},
doi = {10.1038/nature22060},
journal = {Nature (London)},
issn = {0028-0836},
number = 7657,
volume = 546,
place = {United States},
year = {2017},
month = {4}
}

Works referenced in this record:

Graphene spintronics
journal, October 2014

  • Han, Wei; Kawakami, Roland K.; Gmitra, Martin
  • Nature Nanotechnology, Vol. 9, Issue 10
  • DOI: 10.1038/nnano.2014.214

Absence of Ferromagnetism or Antiferromagnetism in One- or Two-Dimensional Isotropic Heisenberg Models
journal, November 1966


Tunable Magnetism and Half-Metallicity in Hole-Doped Monolayer GaSe
journal, June 2015


Modified Sagnac interferometer for high-sensitivity magneto-optic measurements at cryogenic temperatures
journal, August 2006

  • Xia, Jing; Beyersdorf, Peter T.; Fejer, M. M.
  • Applied Physics Letters, Vol. 89, Issue 6
  • DOI: 10.1063/1.2336620

Magnetic properties and energy-mapping analysis
journal, January 2013

  • Xiang, Hongjun; Lee, Changhoon; Koo, Hyun-Joo
  • Dalton Trans., Vol. 42, Issue 4
  • DOI: 10.1039/C2DT31662E

Magnon Renormalization in Ferromagnets Near the Curie Point
journal, October 1962


Localized Magnetic States in Graphene
journal, July 2008


Ultrafast graphene photodetector
journal, October 2009

  • Xia, Fengnian; Mueller, Thomas; Lin, Yu-ming
  • Nature Nanotechnology, Vol. 4, Issue 12, p. 839-843
  • DOI: 10.1038/nnano.2009.292

Exfoliation and Raman Spectroscopic Fingerprint of Few-Layer NiPS3 Van der Waals Crystals
journal, February 2016

  • Kuo, Cheng-Tai; Neumann, Michael; Balamurugan, Karuppannan
  • Scientific Reports, Vol. 6, Issue 1
  • DOI: 10.1038/srep20904

Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator
journal, March 2013


QUANTUM ESPRESSO: a modular and open-source software project for quantum simulations of materials
journal, September 2009

  • Giannozzi, Paolo; Baroni, Stefano; Bonini, Nicola
  • Journal of Physics: Condensed Matter, Vol. 21, Issue 39, Article No. 395502
  • DOI: 10.1088/0953-8984/21/39/395502

Scale-Invariant Quantum Anomalous Hall Effect in Magnetic Topological Insulators beyond the Two-Dimensional Limit
journal, September 2014


Magnetic Moment Formation in Graphene Detected by Scattering of Pure Spin Currents
journal, November 2012


Field Dependence of the Intrinsic Domain Magnetization of a Ferromagnet
journal, December 1940


Room-temperature ferromagnetism in graphite driven by two-dimensional networks of point defects
journal, October 2009

  • Červenka, J.; Katsnelson, M. I.; Flipse, C. F. J.
  • Nature Physics, Vol. 5, Issue 11
  • DOI: 10.1038/nphys1399

Electric-field control of ferromagnetism
journal, December 2000

  • Ohno, H.; Chiba, D.; Matsukura, F.
  • Nature, Vol. 408, Issue 6815
  • DOI: 10.1038/35050040

Proximity-Induced Ferromagnetism in Graphene Revealed by the Anomalous Hall Effect
journal, January 2015


Spin-half paramagnetism in graphene induced by point defects
journal, January 2012

  • Nair, R. R.; Sepioni, M.; Tsai, I-Ling
  • Nature Physics, Vol. 8, Issue 3
  • DOI: 10.1038/nphys2183

Kosterlitz‐Thouless transition in two‐dimensional planar ferromagnet K 2 CuF 4 (invited)
journal, March 1982

  • Hirakawa, K.
  • Journal of Applied Physics, Vol. 53, Issue 3
  • DOI: 10.1063/1.330706

Low-Density Ferromagnetism in Biased Bilayer Graphene
journal, May 2008


Gate-tunable phase transitions in thin flakes of 1T-TaS2
journal, January 2015


Crystallographic, magnetic and electronic structures of a new layered ferromagnetic compound Cr 2 Ge 2 Te 6
journal, January 1995


Direct observation of the layer-dependent electronic structure in phosphorene
journal, September 2016


Large anomalous Hall effect in ferromagnetic insulator-topological insulator heterostructures
journal, August 2014

  • Alegria, L. D.; Ji, H.; Yao, N.
  • Applied Physics Letters, Vol. 105, Issue 5
  • DOI: 10.1063/1.4892353

The domain structure in ultrathin magnetic films
journal, November 1993


Atomic-scale control of graphene magnetism by using hydrogen atoms
journal, April 2016

  • Gonzalez-Herrero, H.; Gomez-Rodriguez, J. M.; Mallet, P.
  • Science, Vol. 352, Issue 6284
  • DOI: 10.1126/science.aad8038

The rise of graphene
journal, March 2007

  • Geim, A. K.; Novoselov, K. S.
  • Nature Materials, Vol. 6, Issue 3, p. 183-191
  • DOI: 10.1038/nmat1849

Theory of Interedge Superexchange in Zigzag Edge Magnetism
journal, June 2009


Spin-Wave Theory of Ferromagnetic Thin Films
journal, June 1963


The valley Hall effect in MoS2 transistors
journal, June 2014


Thickness-Dependent Curie Temperatures of Ultrathin Magnetic Films: Effect of the Range of Spin-Spin Interactions
journal, March 2001


Dimensional crossover in ultrathin Ni(111) films on W(110)
journal, February 1992


Half-metallic graphene nanoribbons
journal, November 2006

  • Son, Young-Woo; Cohen, Marvin L.; Louie, Steven G.
  • Nature, Vol. 444, Issue 7117
  • DOI: 10.1038/nature05180

A ferromagnetic insulating substrate for the epitaxial growth of topological insulators
journal, September 2013

  • Ji, Huiwen; Stokes, R. A.; Alegria, L. D.
  • Journal of Applied Physics, Vol. 114, Issue 11
  • DOI: 10.1063/1.4822092

Linear response approach to the calculation of the effective interaction parameters in the LDA + U method
journal, January 2005