Probing Magnetism in Exfoliated VI₃Layers with Magnetotransport

Abstract

We perform magnetotransport experiments on VI 3 multilayers to investigate the relation between ferromagnetism in bulk and in exfoliated layers. The magnetoconductance measured on field-effect transistors and tunnel barriers shows that the Curie temperature of exfoliated multilayers is T C = 57 K, larger than in bulk (T C,bulk = 50 K). Below T ≈ 40 K, we observe an unusual evolution of the tunneling magnetoconductance, analogous to the phenomenology observed in bulk. Comparing the magnetoconductance measured for fields applied in-or out-of-plane corroborates the analogy, allows us to determine that the orientation of the easy-axis in multilayers is similar to that in bulk, and suggests that the in-plane component of the magnetization points in different directions in different layers. Besides establishing that the magnetic state of bulk and multilayers are similar, our experiments illustrate the complementarity of magnetotransport and magneto-optical measurements to probe magnetism in 2D materials.

Large Orbital Magnetic Moment in VI3

“…Around 36 K a second magnetic phase transition was proposed separating the states with one (at temperatures between 36 and 50 K) and two inequivalent magnetically ordered V sites (at lower temperatures) . In addition, a symmetry lowering from monoclinic to a triclinic structure appears at 32 K upon cooling. , Magnetotransport measurements also show a qualitatively different ferromagnetic state below 40 K, compared to the one between T c and 40 K …”

“…27 In addition, a symmetry lowering from monoclinic to a triclinic structure appears at 32 K upon cooling. 23,28 Magnetotransport measurements also show a qualitatively different ferromagnetic state below 40 K, compared to the one between T c and 40 K. 29 Motivated by the multiple hints for nonzero OM in VI 3 , we utilized the unique ability of X-ray magnetic circular dichroism (XMCD) to determine spin and orbital moments separately 30,31 in an element-specific fashion. Our results confirm the existence of an exceptionally large OM.…”

Strain Tunability of Perpendicular Magnetic Anisotropy in van der Waals Ferromagnets VI3

“…This temperature-dependent magnetic property is consistent with the magnetic susceptibility measurement of the single crystal. However, the Curie temperature ( T c ) is higher than the 49.5 K obtained from magnetic susceptibility measurements, which is related to the thickness-dependent magnetism as reported in refs and . However, the averaged coercivity extracted from MCD measurements is around 1.48 T at 10 K, which is 1 order of magnitude larger than that of the isostructural compound CrI 3 (Figure d).…”

“…The X-ray diffraction (XRD) results in Figure S1a indicate the high quality of the sample. The magnetic susceptibility (χ) measurement in Figure S1b,c reveals a structural transition at a T s value of 78.5 K and a ferromagnetic phase transition at a T c value of 49.4 K. Recent studies show that an easy axis of a VI 3 single crystal at the ferromagnetic state is tilted ∼40° from the crystallographic c -axis. − Under the maximum applied field of 7 T and at 1.8 K (Figure b), the magnetic moments are saturated as 1.156 μ B /V 3+ for H ∥ ab and 1.367 μ B /V 3+ for H ∥ c , which are both smaller than the expected saturated moment of a V 3+ ion, gS = 2 μ B /fu. The reduced magnetic moments are attributed to the non-negligible orbital magnetic moment, which aligned nearly antiparallel with the spin magnetic moment. , Moreover, the out-of-plane curve shows a coercivity field of 1.2 T, much bigger than that of the in-plane (0.1 T).…”

Gate‐Controlled Magnetotransport and Electrostatic Modulation of Magnetism in 2D Magnetic Semiconductor CrPS4

“…In materials such as VI 3 or Cr 2 Ge 2 Te 6 the bandwidth is slightly larger (a few hundreds meV [ 19 ] and 0.5 eV, [ 20,21 ] respectively) and clear transistor action is seen, but even then experiments are drastically limited by the device quality. [ 22–25 ] Very recently, CrSBr—whose bandwidth exceeds 1.5 eV [ 6,26 ] —and NiI 2 —whose bandwidth is estimated to be 0.8–1 eV [ 27 ] —enabled the first realization of FETs operating down to cryogenic temperature, [ 26,28 ] confirming that a large bandwidth is indeed key to observe gate‐induced in‐plane transport at low‐temperatures in these systems. However, in neither of these two compounds electrostatic modification of their magnetic phase boundaries has been reported.…”