Robust Weak Antilocalization Effect Up to ∼120 K in the van der Waals Crystal Fe5-xGeTe2 with Near-Room-Temperature Ferromagnetism.

The van der Waals Fe5-xGeTe2 is a 3d ferromagnetic metal with a high Curie temperature of 275 K. We report herein the observation of an exceptional weak antilocalization (WAL) effect that can persist up to 120 K in an Fe5-xGeTe2 nanoflake, indicating the dual nature with both itinerant and localized magnetism of 3d electrons. The WAL behavior is characterized by the magnetoconductance peak around zero magnetic field and is supported by the calculated localized nondispersive flat band around the Fermi level. The peak to dip crossover starting around 60 K in magnetoconductance is visible, which could be ascribed to temperature-induced changes in Fe magnetic moments and the coupled electronic band structure as revealed by angle-resolved photoemission spectroscopy and first-principles calculations. Our findings would be instructive for understanding the magnetic exchanges in transition metal magnets as well as for the design of next-generation room-temperature spintronic devices.

[1]  C. You,et al.  Direct Observation of Fe‐Ge Ordering in Fe5−xGeTe2 Crystals and Resultant Helimagnetism , 2021, Advanced Functional Materials.

[2]  T. Zhao,et al.  Spontaneous (Anti)meron Chains in the Domain Walls of van der Waals Ferromagnetic Fe5−xGeTe2 , 2020, Advanced materials.

[3]  P. Taylor,et al.  Weak Antilocalization and Anisotropic Magnetoresistance as a Probe of Surface States in Topological Bi2TexSe3−x Thin Films , 2020, Scientific Reports.

[4]  J. Narayan,et al.  Evidence of weak antilocalization in epitaxial TiN thin films , 2020 .

[5]  Junli Zhang,et al.  Weak antilocalization effect and high-pressure transport properties of ScPdBi single crystal , 2019, Applied Physics Letters.

[6]  S. Du,et al.  Quasi-2D Transport and Weak Antilocalization Effect in Few-layered VSe2. , 2019, Nano letters.

[7]  F. Song,et al.  Quantitative Analysis of Weak Antilocalization Effect of Topological Surface States in Topological Insulator BiSbTeSe2. , 2019, Nano letters.

[8]  Xiaodong Xu,et al.  Ferromagnetism Near Room Temperature in the Cleavable van der Waals Crystal Fe5GeTe2. , 2019, ACS nano.

[9]  N. V. Denisov,et al.  Weak Antilocalization at the Atomic-Scale Limit of Metal Film Thickness. , 2018, Nano letters.

[10]  D. Johrendt,et al.  The van der Waals Ferromagnets Fe5-δGeTe2and Fe5-δ-xNixGeTe2- Crystal Structure, Stacking Faults, and Magnetic Properties , 2018, Zeitschrift für anorganische und allgemeine Chemie.

[11]  H. Takagi,et al.  Robust weak antilocalization due to spin-orbital entanglement in Dirac material Sr3SnO , 2018, Nature Communications.

[12]  Changgu Lee,et al.  Hard magnetic properties in nanoflake van der Waals Fe3GeTe2 , 2018, Nature Communications.

[13]  Yi Liu,et al.  Emergence of Kondo lattice behavior in a van der Waals itinerant ferromagnet, Fe3GeTe2 , 2018, Science Advances.

[14]  Michael A. McGuire,et al.  Layer-dependent ferromagnetism in a van der Waals crystal down to the monolayer limit , 2017, Nature.

[15]  S. Louie,et al.  Discovery of intrinsic ferromagnetism in two-dimensional van der Waals crystals , 2017, Nature.

[16]  J. M. Kikkawa,et al.  Monolayer Single-Crystal 1T'-MoTe2 Grown by Chemical Vapor Deposition Exhibits Weak Antilocalization Effect. , 2016, Nano letters.

[17]  A. Neto,et al.  Controlling many-body states by the electric-field effect in a two-dimensional material , 2015, Nature.

[18]  Jie Shan,et al.  Strongly enhanced charge-density-wave order in monolayer NbSe2. , 2015, Nature nanotechnology.

[19]  K. T. Law,et al.  Evidence for two-dimensional Ising superconductivity in gated MoS2 , 2015, Science.

[20]  J. Cha,et al.  Revealing Surface States in In-Doped SnTe Nanoplates with Low Bulk Mobility. , 2014, Nano letters.

[21]  Zhongyuan Liu,et al.  Weak Antilocalization Effect and Noncentrosymmetric Superconductivity in a Topologically Nontrivial Semimetal LuPdBi , 2014, Scientific Reports.

[22]  Yong Wang,et al.  Competing weak localization and weak antilocalization in ultrathin topological insulators. , 2013, Nano letters.

[23]  Thomas A. Lograsso,et al.  Weak Anti-localization and Quantum Oscillations of Surface States in Topological Insulator Bi2Se2Te , 2012, Scientific Reports.

[24]  Yi Cui,et al.  Weak antilocalization in Bi2(Se(x)Te(1-x))3 nanoribbons and nanoplates. , 2012, Nano letters.

[25]  P. Kim,et al.  Experimental observation of the quantum Hall effect and Berry's phase in graphene , 2005, Nature.

[26]  Andre K. Geim,et al.  Electric Field Effect in Atomically Thin Carbon Films , 2004, Science.

[27]  Jonathan P. Bird,et al.  Recent experimental studies of electron dephasing in metal and semiconductor mesoscopic structures , 2002 .