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The exchange bias effect is extremely expected in 2D van der Waals (vdW) ferromagnetic (FM)/antiferromagnetic (AFM) heterostructures due to the high‐quality interface. CrOCl possesses strong magnetic anisotropy at 2D limit, and is an ideal antiferromagnet for constructing FM/AFM heterostructures to explore the exchange bias effect. Here, the exchange bias effect in Fe3GeTe2 (FGT)/CrOCl heterostructures through both anomalous Hall effect (AHE) and reflective magnetic circular dichroism (RMCD) measurements is studied. In the AHE measurements, the exchange bias field (HEB) at 3 K exhibits a distinct increase from ≈150 Oe to ≈450 Oe after air exposure, and such variation is attributed to the formation of an oxidized layer in FGT by analyzing the cross‐sectional microstructure. The HEB is successfully tuned by changing the FGT/CrOCl thickness and the cooling field. Furthermore, a larger HEB of ≈750 Oe at 1.7 K in FGT/CrOCl heterostructure through RMCD measurements is observed, and it is proposed that the larger HEB in RMCD measurements is related to the distribution of uncompensated spins at the interface. This work reveals several intriguing phenomena of the exchange bias effect in 2D vdW magnetic systems, which paves the way for the study of related spintronic devices. The exchange bias effect in ferro‐/antiferromagnetic Fe3GeTe2 (FGT)/CrOCl heterostructure is thoroughly studied through anomalous Hall effect and reflective magnetic circular dichroism (RMCD) measurements. The bias field (HEB) reveals anomaly increase with the presence of an oxidized layer in FGT. The larger HEB in the RMCD measurements can be related to the distribution of uncompensated spins.

Artificial heterostructures are typically created by layering distinct materials, thereby giving rise to unique characteristics different from their individual components. Herein, two-dimensional α-MnSe nanosheets with a non-layered structure were fabricated on Ga0.6Fe1.4O3 (GFO) films. The superior crystalline properties of MnSe/GFO heterostructures were confirmed through structural and morphological analyses. The remanent polarization is around 1.5 μC/cm2 and the leakage current density can reach 2 × 10−3 A/cm2 under 4 V. In addition, the piezo-response force microscopy amplitude and phase images further supported the ferroelectric property. The significant improvement of coercive field and saturated magnetization, along with the antiparallel signals of Mn and Fe ions observed through synchrotron X-ray analyses, suggest the presence of magnetic interaction within the MnSe/GFO heterostructure. Finally, the excellent photodetector with a photo detectivity of 6.3 × 108 Jones and a photoresponsivity of 2.8 × 10−3 A·W−1 was obtained under 532 nm in the MnSe/GFO heterostructure. The characteristics of this heterostructure, which include multiferroic, magnetic exchange bias effect, and photodetection capabilities, are highly beneficial for multifunctional devices.

The La 2 FeCoO 6 ceramic was synthesized via the sol–gel route, and their temperature-dependent exchange bias (EB) effects have been analyzed at different magnetic fields. XRD investigation reveals that at a lower temperature, the monoclinic structure with the P2 1 /n space group was maintained, whereas, from room temperature to 450 K, the rhombohedral structure with the R3c space group was noticed. The tolerance factor suggested the presence of distortion, and the XPS analysis of Fe and Co confirms the defect sites in La 2 FeCoO 6 . Hence, the variety of magnetic phases formed during the FC and ZFC processes resulted in unidirectional anisotropy. Negative field cooling magnetization was observed in M-T measurements, and ferromagnetic clusters were detected at room temperature M-H measurements. Negative EB fields and upward shifts in hysteresis were observed at low temperatures. The hysteresis and EB fields changed below the Neel transition, with a transition from positive to negative EB observed with increasing magnetic field and temperature. The observed EB was attributed to the pinning effect of surface spins in interfacial frozen glassy states at the interface of large ferrimagnetic grains.

Magnetic properties of Y 0.67 Sr 0.33 MnO 3 (YSMO) and La 0.67 Sr 0.33 MnO 3 (LSMO) thin films heterostructures (YSMO/LSMO) deposited on single-crystalline (001) SrTiO 3 (STO), (001) LaAlO 3 (LAO) and MgO substrates using pulsed laser deposition technique were investigated. Magnetization ( M ) vs. the applied field ( H ) measurements revealed shift in hysteresis loop showing the exchange bias effect of about 80 Oe for the heterostructures on LAO substrate, which was absent for those on STO substrates. In order to investigate this, single-layer LSMO layers were deposited on these substrates. X-ray diffraction patterns revealed significant compressive strain and a weaker tensile strain for LSMO films on LAO and STO substrates, respectively. Raman spectroscopy measurements further confirmed the lattice mismatch-induced strain in LSMO layer on LAO substrate. These different strain conditions in LSMO films on both the substrates are suggested to be contributing to the emergence of different magnetic ground states in these systems, which could be leading to pinning of spins at the interface and resulting in a significant exchange bias effect (EBE) on LAO substrate.

The geometry–dependent magnetoelectric (ME) and exchange bias (EB) effects of the nano ME sensor were investigated. The sensor consisted of the Longitudinal–Transverse (L–T) mode bi–layer bar structure comprising the ferromagnetic (FM) and ferroelectric (FE) materials and the anti–ferromagnetic (AFM) material. The bi–layer ME coefficient was derived from constitutive equations and Newton’s second law. The trade–off between peak ME coefficient and optimal thickness ratio was realized. At the frequency × structure length = 0.1 and 1200, minimum and maximum peak ME coefficients of the Terfenol–D/PZT bi-layer were around 1756 and 5617 mV/Oe·cm, respectively, with 0.43 and 0.19 optimal thickness ratios, respectively. Unfortunately, the bi-layer could not distinguish the opposite magnetic field directions due to their similar output voltages. PtMn and Cr2O3, the AFM, were introduced to produce the EB effect. The simulation results showed the exchange field starting at a minimum PtMn thickness of 6 nm. Nevertheless, Cr2O3 did not induce the exchange field due to its low anisotropy constant. The tri–layer ME sensor consisting of PZT (4.22 nm)/Terfenol–D (18 nm)/PtMn (6 nm) was demonstrated in sensing 2 Tbit/in2 magnetic bits. The average exchange field of 5100 Oe produced the output voltage difference of 12.96 mV, sufficient for most nanoscale magnetic sensing applications.

The martensitic phase transition and exchange bias effect of the Ni-Mn-based ferromagnetic shape memory alloys (FSMAs) Ni45Co5Mn37In13 (Ni-Co-Mn-In) films are investigated in this paper. The martensitic transformation properties of the Ni-Co-Mn-In alloy target material are manipulated by the process of electric arc melting, melt-fast quenching, and high-temperature thermal pressure. The Ni-Co-Mn-In alloy films with martensite phase transition characteristics are obtained by adjusting deposition parameters on the (001) MgO substrate, which shows a significant exchange bias (EB) effect at different temperatures. With increasing sputtering power and time, the film thickness increases, resulting in a gradual relaxation of the constraints at the interface between the film and the substrate (the interfacial strain decreases as the increase of thin film thickness), which promotes the martensite phase transition. Between zero-field cooling (ZFC) and field-cooled (FC) curve obvious division zone, the decrease of exchange bias field (HEB) and coercive force field (Hc) with an increase in test temperature is due to ferromagnetic (FM) interaction begins to dominate, resulting in a reduction of antiferromagnetic (AFM) anisotropy at the interface. The maximal HEB and Hc reach ~465.7 Oe and ~306.9 Oe at 5 K, respectively. The manipulation of the martensitic transformation and EB effect of the Ni-Co-Mn-In alloy films demonstrates potential application in the field of information and spintronics.

AbstractCo$$_{3}$$3Sn$$_{2}$$2S$$_{2}$$2 is a ferromagnetic Weyl semimetal that has been the subject of intense scientific interest due to its large anomalous Hall effect. We show that the coupling of this material’s topological properties to its magnetic texture leads to a strongly exchange biased anomalous Hall effect. We argue that this is likely caused by the coexistence of ferromagnetism and geometric frustration intrinsic to the kagome network of magnetic ions, giving rise to spin-glass behavior and an exchange bias.

Recently, Delta-E effect magnetic field sensors based on exchange-biased magnetic multilayers have shown the potential of detecting low-frequency and small-amplitude magnetic fields. Their design is compatible with microelectromechanical system technology, potentially small, and therefore, suitable for arrays with a large number N of sensor elements. In this study, we explore the prospects and limitations for improving the detection limit by averaging the output of N sensor elements operated in parallel with a single oscillator and a single amplifier to avoid additional electronics and keep the setup compact. Measurements are performed on a two-element array of exchange-biased sensor elements to validate a signal and noise model. With the model, we estimate requirements and tolerances for sensor elements using larger N. It is found that the intrinsic noise of the sensor elements can be considered uncorrelated, and the signal amplitude is improved if the resonance frequencies differ by less than approximately half the bandwidth of the resonators. Under these conditions, the averaging results in a maximum improvement in the detection limit by a factor of N. A maximum N≈200 exists, which depends on the read-out electronics and the sensor intrinsic noise. Overall, the results indicate that significant improvement in the limit of detection is possible, and a model is presented for optimizing the design of delta-E effect sensor arrays in the future.

The last several decades have witnessed a shift away from a fully rational paradigm of financial markets toward one in which investor behavior is influenced by psychological biases. Two principal factors have contributed to this evolution: a body of evidence showing how psychological bias affects the behavior of economic actors; and an accumulation of evidence that is hard to reconcile with fully rational models of security market trading volumes and returns. In particular, asset markets exhibit trading volumes that are high, with individuals and asset managers trading aggressively, even when such trading results in high risk and low net returns. Moreover, asset prices display patterns of predictability that are difficult to reconcile with rational-expectations–based theories of price formation. In this paper, we discuss the role of overconfidence as an explanation for these patterns.

We utilize ocean 10-m wind speed (U10m) from the microwave Multi-sensor Advanced Climatology data set to examine the coupling between convective cloud and precipitation processes, synoptic state, and U10m and to evaluate the representation of U10m in global climate models (GCMs). We find that midlatitude U10m is underestimated by GCMs relative to observations. We examine two potential mechanisms to explain this model behavior: cold pool formation in cold air outbreaks (CAOs) associated with downdrafts that enhance U10m and sea surface temperature (SST) gradients affecting U10m through thermally forced surface winds at regional scales. When the effects of the CAO index (M) and SST gradients on U10m are accounted for, a relationship between GCM horizontal resolution and U10m appears. The strongest correlation between resolution and U10m is over the western boundary currents characterized by frequent CAOs atop strong SST gradients which drives the strongest surface fluxes on Earth.