Probing van der Waals magnetic surface and interface via circularly polarized X-rays

Advances in research of magnetic two-dimensional van der Waals (2D vdW) materials have opened up new opportunities in miniaturization of spintronic devices at the atomically thin limit. One major research thrust, which is the subject of this review, is that the magnetism of 2D vdW materials and their derived hetero-interface may be significantly affected by the local atomic geometry and environment. As a result, there is a pressing need for powerful advanced technique to characterize magnetic vdW surface and interface. Circularly polarized X-rays from synchrotron radiation light sources are key to this endeavor, as they can probe the microscopic magnetism of a specific element, for their atomic sensitivity, element-specificity, core-level excitation as well as capability of separation for the spin and orbit moments. We review a series of representative experimental achievements, exploiting circularly polarized X-rays, in (1) 2D vdW magnet, (2) magnetic metal/vdW interface, (3) molecule/vdW interface as well as (4) vdW/2D interface. On the basis of the review, advantages of probing magnetic vdW surface and interface by circularly polarized X-rays are presented, and challenges and opportunities are also discussed.

[1]  J. Pospíšil,et al.  Large Orbital Magnetic Moment in VI3 , 2022, Nano letters.

[2]  Geunsik Lee,et al.  Role Of Orbital Bond and Local Magnetism In Fe3GeTe2 and Fe4GeTe2: Implication For Ultrathin Nano Devices , 2022, ACS Applied Nano Materials.

[3]  J. C. Loudon,et al.  History-dependent domain and skyrmion formation in 2D van der Waals magnet Fe3GeTe2 , 2022, Nature Communications.

[4]  M. Batzill,et al.  Van der Waals epitaxy growth of 2D ferromagnetic Cr(1+δ)Te2 nanolayers with concentration-tunable magnetic anisotropy , 2022, Applied Physics Reviews.

[5]  Wenqing Liu,et al.  Bulk-Like Magnetic Moment of Epitaxial 2-D Superlattices , 2022, IEEE Transactions on Magnetics.

[6]  M. Phan,et al.  Exchange bias and interface-related effects in two-dimensional van der Waals magnetic heterostructures: Open questions and perspectives , 2022, Journal of Alloys and Compounds.

[7]  Wenqing Liu,et al.  Probing the atomic-scale ferromagnetism in van der Waals magnet CrSiTe3 , 2021, Applied Physics Letters.

[8]  Masatoshi Suzuki,et al.  Magnetic anisotropy of the van der Waals ferromagnet Cr2Ge2Te6 studied by angular-dependent x-ray magnetic circular dichroism , 2021, Physical Review Research.

[9]  P. Chu,et al.  Graphene-mediated ferromagnetic coupling in the nickel nano-islands/graphene hybrid , 2021, Science Advances.

[10]  A. Marty,et al.  Large-scale epitaxy of two-dimensional van der Waals room-temperature ferromagnet Fe5GeTe2 , 2021, npj 2D Materials and Applications.

[11]  T. Hitosugi,et al.  Absence of ferromagnetism in MnBi2Te4/Bi2Te3 down to 6 K , 2021 .

[12]  David J. Singh,et al.  Room-temperature intrinsic ferromagnetism in epitaxial CrTe2 ultrathin films , 2021, Nature Communications.

[13]  Namdong Kim,et al.  Surface oxidation in a van der Waals ferromagnet Fe3-xGeTe2 , 2021 .

[14]  C. Hsu,et al.  Itinerant ferromagnetism mediated by giant spin polarization of the metallic ligand band in the van der Waals magnet Fe5GeTe2 , 2021, 2101.01324.

[15]  Tetsuya Nakamura,et al.  Presence of X-Ray Magnetic Circular Dichroism Signal for Zero-Magnetization Antiferromagnetic State. , 2020, Physical review letters.

[16]  T. Hesjedal,et al.  Depth-Resolved Magnetization Dynamics Revealed by X-Ray Reflectometry Ferromagnetic Resonance. , 2020, Physical review letters.

[17]  Y. Z. Wu,et al.  Creation of skyrmions in van der Waals ferromagnet Fe3GeTe2 on (Co/Pd)n superlattice , 2020, Science Advances.

[18]  S. Parkin,et al.  Intrinsic 2D-XY ferromagnetism in a van der Waals monolayer , 2020, Science.

[19]  A. Locatelli,et al.  In-plane magnetic domains and Néel-like domain walls in thin flakes of the room temperature CrTe2 van der Waals ferromagnet. , 2020, ACS applied materials & interfaces.

[20]  A. Wee,et al.  Exchange bias in van der Waals CrCl3/Fe3GeTe2 heterostructures. , 2020, Nano letters.

[21]  A. Wee,et al.  Can Reconstructed Se‐Deficient Line Defects in Monolayer VSe2 Induce Magnetism? , 2020, Advanced materials.

[22]  C. Shan,et al.  Tunable Room-temperature Ferromagnetism in two-dimensional Cr2Te3. , 2020, Nano letters.

[23]  S. Loth,et al.  Quantum dynamics of a single molecule magnet on superconducting Pb(111) , 2020, Nature Materials.

[24]  A. Wee,et al.  Two-dimensional ferromagnetic superlattices , 2019, National science review.

[25]  A. Wee,et al.  Van der Waals magnets: Wonder building blocks for two‐dimensional spintronics? , 2019, InfoMat.

[26]  Hyung-jun Kim,et al.  Controlling the magnetic anisotropy of van der Waals ferromagnet Fe3GeTe2 through hole doping. , 2019, Nano letters.

[27]  M. Nakano,et al.  Intrinsic 2D Ferromagnetism in V5Se8 Epitaxial Thin Films. , 2019, Nano letters.

[28]  S. van Dijken,et al.  Electronic and magnetic characterization of epitaxial VSe2 monolayers on superconducting NbSe2 , 2019, Communications Physics.

[29]  P. Torelli,et al.  Proximity-induced ferromagnetism and chemical reactivity in few-layer VSe2 heterostructures , 2019, Physical Review B.

[30]  S. Pennycook,et al.  Chemically Exfoliated VSe2 Monolayers with Room‐Temperature Ferromagnetism , 2019, Advanced materials.

[31]  Y. Feng,et al.  Magnetic Transition in Monolayer VSe2 via Interface Hybridization. , 2019, ACS nano.

[32]  Wei Chen,et al.  Metallic 1T Phase, 3d1 Electronic Configuration and Charge Density Wave Order in Molecular Beam Epitaxy Grown Monolayer Vanadium Ditelluride. , 2019, ACS nano.

[33]  G. Brocks,et al.  Evidence of Spin Frustration in a Vanadium Diselenide Monolayer Magnet , 2019, Advanced materials.

[34]  Jingsheng Chen,et al.  Giant Enhancements of Perpendicular Magnetic Anisotropy and Spin‐Orbit Torque by a MoS2 Layer , 2019, Advanced materials.

[35]  S. Pennycook,et al.  Ferromagnet/Two-Dimensional Semiconducting Transition-Metal Dichalcogenide Interface with Perpendicular Magnetic Anisotropy. , 2019, ACS nano.

[36]  L. B. Duffy,et al.  Electronic Structure and Enhanced Charge-Density Wave Order of Monolayer VSe2. , 2018, Nano letters.

[37]  Xiaodong Xu,et al.  Giant tunneling magnetoresistance in spin-filter van der Waals heterostructures , 2018, Science.

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

[39]  H. Wadati,et al.  Capturing ultrafast magnetic dynamics by time-resolved soft x-ray magnetic circular dichroism , 2017, 1701.03156.

[40]  V. Sessi,et al.  Graphene-Induced Magnetic Anisotropy of a Two-Dimensional Iron Phthalocyanine Network. , 2015, The journal of physical chemistry letters.

[41]  N. Brookes,et al.  Ferromagnetic Exchange Coupling between Fe Phthalocyanine and Ni(111) Surface Mediated by the Extended States of Graphene , 2014 .

[42]  R. Landers,et al.  Patterning Quasi-Periodic Co 2D-Clusters underneath Graphene on SiC(0001) , 2014 .

[43]  R. A. Stokes,et al.  A ferromagnetic insulating substrate for the epitaxial growth of topological insulators , 2013 .

[44]  Ying Dai,et al.  Evidence of the existence of magnetism in pristine VX₂ monolayers (X = S, Se) and their strain-induced tunable magnetic properties. , 2012, ACS nano.

[45]  J. Fréchet,et al.  Molecular design and ordering effects in π-functional materials for transistor and solar cell applications. , 2011, Journal of the American Chemical Society.

[46]  K. Novoselov.  Nobel Lecture: Graphene: Materials in the Flatland , 2011 .

[47]  H. Zhang,et al.  Bulk sensitive x-ray absorption spectroscopy free of self-absorption effects , 2010, 1001.1925.

[48]  J. Eckstein,et al.  Suppressed magnetization at the surfaces and interfaces of ferromagnetic metallic manganites , 2006, Journal of physics. Condensed matter : an Institute of Physics journal.

[49]  T. Cren,et al.  Uniform magnetic properties for an ultrahigh-density lattice of noninteracting co nanostructures. , 2005, Physical review letters.

[50]  Jack C. Rife,et al.  Experimental and theoretical comparison between absorption, total electron yield, and fluorescence spectra of rare-earth M{sub 5} edges , 1997 .

[51]  H. Ebert.  Magneto-optical effects in transition metal systems , 1996 .

[52]  Joachim Stöhr,et al.  X-ray magnetic circular dichroism spectroscopy of transition metal thin films , 1995 .

[53]  Thole,et al.  X-ray circular dichroism and local magnetic fields. , 1993, Physical review letters.

[54]  Thole,et al.  X-ray circular dichroism as a probe of orbital magnetization. , 1992, Physical review letters.

[55]  Chen,et al.  Soft-x-ray magnetic circular dichroism at the L2,3 edges of nickel. , 1990, Physical review. B, Condensed matter.

[56]  M. Mannini,et al.  Single-Molecule Magnets on Surfaces , 2014 .