Title: Revealing room temperature ferromagnetism in exfoliated Fe₅GeTe₂ flakes with quantum magnetic imaging

Abstract

Van der Waals (vdW) material Fe₅GeTe₂, with its long-range ferromagnetic ordering near room temperature, has significant potential to become an enabling platform for implementing novel spintronic and quantum devices. To pave the way for applications, it is crucial to determine the magnetic properties when the thickness of Fe₅GeTe₂ reaches the few-layers regime. However, this is highly challenging due to the need for a characterization technique that is local, highly sensitive, artifact-free, and operational with minimal fabrication. Prior studies have indicated that Curie temperature T_C can reach up to close to room temperature for exfoliated Fe₅GeTe₂ flakes, as measured via electrical transport; there is a need to validate these results with a measurement that reveals magnetism more directly. Here, we investigate the magnetic properties of exfoliated thin flakes of vdW magnet Fe₅GeTe₂ via quantum magnetic imaging technique based on nitrogen vacancy centers in diamond. Through imaging the stray fields, we confirm room-temperature magnetic order in Fe₅GeTe₂ thin flakes with thickness down to 7 units cell. The stray field patterns and their response to magnetizing fields with different polarities is consistent with previously reported perpendicular easy-axis anisotropy. Furthermore, we perform imaging at different temperatures and determine the Curie temperature of the flakesmore » at ≈300 K. These results provide the basis for realizing a room-temperature monolayer ferromagnet with Fe₅GeTe₂. This work also demonstrates that the imaging technique enables rapid screening of multiple flakes simultaneously as well as time-resolved imaging for monitoring time-dependent magnetic behaviors, thereby paving the way towards high throughput characterization of potential two-dimensional (2D) magnets near room temperature and providing critical insights into the evolution of domain behaviors in 2D magnets due to degradation.« less

Authors:

Chen, Hang  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-2341-3815"

Asif, Shahidul ^[1]; Whalen, Matthew ^[1]; Támara-Isaza, Jeyson ^[2]; Luetke, Brennan ^[1]; Wang, Yang ^[1]; Wang, Xinhao ^[1]; Ayako, Millicent ^[1]; Lamsal, Saurabh ^[1]; May, Andrew F.  ^[3];

• Search DOE PAGES for author "May, Andrew F."
• Search DOE PAGES for ORCID "0000-0003-0777-8539"

McGuire, Michael A. ^[3]; Chakraborty, Chitraleema ^[1]; Xiao, John Q.  ^[1];

• Search DOE PAGES for author "Xiao, John Q."
• Search DOE PAGES for ORCID "0000-0001-7805-8155"

Ku, Mark H.  ^[1]

• Search DOE PAGES for author "Ku, Mark H."
• Search DOE PAGES for ORCID "0000-0003-3144-3069"

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+ Show Author Affiliations

1. Univ. of Delaware, Newark, DE (United States)
2. Univ. of Delaware, Newark, DE (United States); Universidad Nacional de Colombia, Bogotá D.C. (Colombia)
3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Publication Date:

Mon Mar 07 00:00:00 EST 2022

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division; National Science Foundation (NSF); University of Delaware

OSTI Identifier:

1872847

Grant/Contract Number:  

AC05-00OR22725; 2011824; 1904076; 312181

Resource Type:

Accepted Manuscript

Journal Name:

2D Materials

Additional Journal Information:

Journal Volume: 9; Journal Issue: 2; Journal ID: ISSN 2053-1583

Publisher:

IOP Publishing

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Fe5GeTe2; 2D magnet; quantum sensing