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Itinerant ferromagnetism in van der Waals Fe5x GeTe2 crystals above room temperature

Journal Article · · Physical Review B
 [1];  [1];  [2];  [1];  [1];  [1];  [3];  [1];  [4];  [5];  [1];  [1]
  1. Univ. of California, Berkeley, CA (United States)
  2. Yanshan University (China)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS) & Materials Sciences Division
  4. Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Physics
  5. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division
Two-dimensional (2D) van der Waals (vdW) magnets have recently attracted increasing attention, as they provide a novel system for exploring 2D magnetism. However, intrinsic ferromagnetism in 2D systems has almost exclusively been observed at low temperatures, limiting their technological relevance. FeN GeTe2 ( N=3 , 4, and 5) systems are currently becoming the most attractive 2D vdW materials due to their relatively high Curie temperatures and large saturation magnetization. However, the nature of their complex yet intriguing magnetic behaviors is still unclear, in part due to the multiple inequivalent iron sites and iron vacancies. In this study, we show evolution of magnetic ordering transitions in Fe5x GeTe2 with high Curie temperature and a strong saturation magnetization using photoemission electron microscopy and transport measurements. At 275 K, the ferromagnet transitions to a ferrimagnet, and below 110 K transitions to a state with glassy clusters. These are evidenced from temperature-dependent magnetic stripe domain evolution and anisotropic magnetoresistance measurements. Our findings show a clear magnetic ground state of Fe5x GeTe2 at room temperature which signals that Fe5x GeTe2 system is a very promising candidate for spintronic devices and provides a material design pathway to further increase the Curie temperature and saturation moments in vdW ferromagnets.
Research Organization:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division
Grant/Contract Number:
AC02-05CH11231
OSTI ID:
1775404
Journal Information:
Physical Review B, Journal Name: Physical Review B Journal Issue: 6 Vol. 102; ISSN 2469-9950
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

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