Probing Ferrimagnetic Semiconductor with Enhanced Negative Magnetoresistance: 2D Chromium Sulfide

Abstract

Magnetic 2D materials have emerged as a great interest in spintronics due to atomic thickness scaling, low energy switching, and ease in the manipulation of spins. This report demonstrates a facile, bottom‐up, chemical vapor deposition approach for non‐van der Waals (non‐vdWs), 2D chromium (III) sulfide (Cr2S3) with c‐axis orientation, out‐of‐plane magnetic anisotropy (easy axis), and ferrimagnetic ordering. Importantly, the anisotropic magnetic saturation and resistivity of 10.23 mΩ cm reveal a narrow bandgap ferrimagnetism in Cr2S3 (∆EActivation ≈ 22 meV and Eg ≈ 40 meV). The prototype lateral spin‐channel Al/Cr2S3/Al devices exhibit a negative magnetoresistance of ≈25% and ≈15% at 100 K (below Néel temperature) for few‐layer (≈8 nm) and thin‐film (≈50 nm) device structures, respectively, owing to itinerant ferrimagnetism of Cr2S3. The magnetic field‐induced spin polaron formations are quite resilient and enhance the field‐dependent carrier conduction, making it greatly useful for negative magnetoresistance operation. These prototype Al/Cr2S3/Al structures have demonstrated a low power (≈2 µW for 8 µm channel at 10 µA current) operation with a negative field‐dependent resistance coefficient (rM) of ≈−5 × 10−4 Oe−1. The computed rM magnitude is tenfold higher than the bulk Cr2S3. This study identifies the potential of non‐vdW Cr2S3 toward new and robust 2D‐based spintronic applications.

A New Group of 2D Non‐van der Waals Materials with Ultra Low Exfoliation Energies

“…The first representatives realized in experiment by a special chemical exfoliation process were hematene [21] and ilmenene [22] obtained from the earth-abundant ores hematite (α-Fe 2 O 3 ) and ilmenite (FeTiO 3 ), followed by a few others. [23][24][25][26][27][28][29][30][31][32][33][34][35][36] Their explicit derivation from existing bulk compounds (ores) makes these systems distinct from many other suggested synthetic 2D materials without layered bulk allotropes [37,38] and unlike, e.g., silicene or borophene, [39] these materials do not need to strongly interact with a substrate to be stable. From the computational side, a recent data-driven search on non-vdW 2D systems outlined 28 candidates with a variety of appealing electronic and magnetic properties.…”

Data-Driven Quest for Two-Dimensional Non-van der Waals Materials

“…[21][22][23]25,26 Unexpectedly, a new direction in the research on 2D systems was opened in 2018, after the experimental realization of atomically thin sheets from non-vdW bonded compounds by a special chemical exfoliation process. 29,30 The first representatives of these non-vdW 2D materials were hematene and ilmenene obtained from the earth-abundant ores hematite (α-Fe 2 O 3 ) and ilmenite (FeTiO 3 ), followed by other systems derived from chromite (FeCr 2 O 4 ), 31 magnetite (Fe 3 O 4 ), 32 pyrite (FeS 2 ), 33,34 chromium sulfide, 35 manganese selenide (α-MnSe 2 ), 36 metal diborides, 37 boro-carbides, 38 and diamondlike germanium (α-Ge). 39 While traditional vdW compounds have chemically saturated bonds at the surface of 2D subunits, the aforementioned materials show qualitatively new features.…”

Growth of wafer-scale chromium sulphide and selenide semiconductor films

“…Even so, the 2D non-layered chromium chalcogenides still draw great attentions due to the diverse properties. The compound of chromium sulphides is mainly Cr 2 S 3 , and it can be grown via chemical vapour deposition (CVD) method [27][28][29]. The CVD method is usually adopted for growing most 2D layered TMDCs [30].…”