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Exploitation and enhancement of the mechanical strain to modulate the magnetic properties are crucial for developing conformal wearable magnetic-electronic devices. However, the mechanical strain how to regulate the magnetic properties remains unclear for flexible thin film. Here, (111)-oriented SrRuO3 thin films are epitaxially grown on flexible mica substrates, and the influence of the mechanical bending on magnetic properties is studying by altering the curvature of the SrRuO3/BaTiO3/Mica heterostructure. The results show that the phase transition temperature does not reveal a significant dependence on both of convex and concave bending but they play a contrary role on the magnetic entropy change. Namely, the tensile stress (convex) increases the magnetic entropy change while the compressive stress (concave) decreases it. Moreover, based on the scale analysis method, we find that both bending states are directly correlated with the change of critical phase transition behavior. We think that the variation of domain wall configuration due to mechanical bending is the main reason for the change of magnetic properties. This study therefore not only identifies a strong magnetic property correlation in the mechanical strain, but also offers an avenue to improve flexible electronic devices with optimized performance.

Manufacture and characterizations of perovskite-mica van der Waals epitaxy heterostructures are a critical step to realize the application of flexible devices. However, the fabrication and investigation of the van der Waals epitaxy architectures grown on mica substrates are mainly limited to (111)-oriented perovskite functional oxide thin films up to now and buffer layers are highly needed. In this work, we directly grew La0.7Sr0.3MnO3 (LSMO) thin films on mica substrates without using any buffer layer. By the characterizations of x-ray diffractometer and scanning transmission electron microscopy, we demonstrate the epitaxial growth of the (110)-oriented LSMO thin film on the mica substrate. The LSMO thin film grown on the mica substrate via van der Waals epitaxy adopts domain matching epitaxy instead of conventional lattice matching epitaxy. Two kinds of domain matching relationships between the LSMO thin film and mica substrate are sketched by Visualization for Electronic and STructural Analysis software and discussed. A decent ferromagnetism retains in the (110)-oriented LSMO thin film. Our work demonstrates a new pathway to fabricate (110)-oriented functional oxide thin films on flexible mica substrates directly.

Tricritical phenomenon appearing in multiple phases is a fundamental and attractive issue in condensed-matter physics. In this work, a field-modulated tricritical phenomenon is realized in single-crystal PrCu9Sn4. The magnetization under variable directions of field indicates strong magnetic anisotropy in PrCu9Sn4, which reveals ferromagnetic coupling for H//c. A paramagnetic-to-ferromagnetic magnetic transition occurs with H//c at T C = 11.7 K, which is evidenced to be of a first-ordered type. The systematical study of the critical behavior gives that β = 0.195(8), γ = 0.911(1), and δ = 0.0592(1) for H//c consistent with a tricritical mean-field model, which suggests a field-modulated tricritical phenomenon. A detailed H − T phase diagram around the tricritical point (TCP) is constructed for single-crystal PrCu9Sn4 for H//c, where ferromagnetic state, forced ferromagnetic phase and paramagnetic state meet at the TCP (H tr = 799 kOe, T tr = 11.3 K). The single-crystal PrCu9Sn4 supplies a platform to deep investigate the field-modulated magnetic couplings and tricritical phenomenon.

Large-scale growth of two-dimensional (2D) ferromagnetic thin films will provide an ideal platform for studying 2D magnetism and active spintronic devices. However, controllable growth of 2D ferromagnets over large areas faces tremendous challenges. Herein, we report a large-area growth of 2D ferromagnetic single-crystal thin films Cr4Te5 on Al2O3 (0001) substrates using pulsed laser deposition. X-ray diffraction patterns and atomic force microscopy detection confirm that all thin films have high quality epitaxy together with being atom-level smooth. Magnetic measurements show the persistence of ferromagnetic ordering state to above room temperature, with a Curie temperature ∼320 K, atomic magnetic moment ∼0.307 μ B /Cr, and the easy-magnetization axis in the film plane. Comparing with bulk Cr4Te5 single-crystal, the critical exponent β = 0.491 indicates that the magnetic interactions of the thin film obey the mean-field model rather than the 3D Heisenberg model. This work will open an avenue for growing large-scale 2D ferromagnets and developing room temperature 2D magnet-based nanodevices.

Generally, magnetic anisotropy is a common feature of a layered magnetic material, the exploration of which plays a key role in understanding the intrinsic magnetic couplings. In this work, we have studied the field-induced magnetic transitions for layered YbNi3Al9 as the external magnetic field is applied perpendicularly ([Formula: see text]) and parallel (H//c) to the c-axis. We find that two independent universal curves of magnetic entropy change [[Formula: see text]] can be fitted out for [Formula: see text] and H//c, respectively. According to the universality principle of scaling, the extra magnetic entropy changes ([Formula: see text] and [Formula: see text]) caused by the field-induced magnetic phase transitions can be obtained for [Formula: see text] and H//c. The two-dimensional [Formula: see text] plots as functions of field and temperature are constructed, which clearly reveal the evolutions of the magnetic entropy changes resulted from the two different field-induced magnetic phase transitions. It is suggested that the [Formula: see text] for [Formula: see text] with the maximum at (3.2 K, 4.1 kOe) originates from a field-modulated helicoidal spin-texture. However, the [Formula: see text] for H//c with the maximum at (3.4 K, 13.8 kOe) stems from a field-induced canted antiferromagnetic state.

The ferromagnetic semi-conductive Cr2Ge2Te6 with van der Waals bonded layers is prominent for characteristics of easy exfoliation and tunablility, which make it a potential candidate for spintronic application. Although the magnetism has been investigated intensively, the transport property is rarely studied, which is very important for the realization of its application. In this work, the electronic transport of Cr2Ge2Te6 is investigated under external magnetic field with variable directions. The angle-dependent resistance shows absolute isotropic property in the ab-plane. However, it displays anisotropic characteristic when the magnetic field is rotated from the ab-plane to the c-axis. The resistance reaches the maximum when H//c while it is the minimum when H//ab. Moreover, the field-dependent resistance of Cr2Ge2Te6 shows a positive magnetoresistance (MR) effect when H//c but a negative one when H//ab. We suggest that the anisotropic MR behaviors of Cr2Ge2Te6 can be understood theoretically within the framework based on the exchange interaction between the carriers and local magnetic moments.

The magnetization of Mn-intercalated layered MnNb3S6 single crystal has been systematically investigated. The angle-dependent magnetization ([Formula: see text], [Formula: see text], and [Formula: see text]) displays that the magnetization of MnNb3S6 with [Formula: see text] is much stronger than that with H//c, but no magnetic anisotropy within the ab-plane. In addition, a field-induced magnetic phase transition is found when [Formula: see text]. The investigation of the critical behavior gives the critical exponents [Formula: see text], [Formula: see text], and [Formula: see text] with [Formula: see text] K, which belong to the universality class of three-dimensional Heisenberg model. The critical behavior and exponents indicate that the magnetic coupling in MnNb3S6 is of an isotropic short-range type. Based on universality scaling, the H - T phase diagram with [Formula: see text] is constructed. The magnetic behaviors and phase diagram of MnNb3S6 are analogous to those of CrNb3S6 which exhibits a chiral magnetic soliton lattice.

The magnetic properties and stability in Nd0.5(1 − x)Ca0.5(1 + x)Mn1 − xTixO3 (0.0 ≤ x ≤ 0.10) polycrystalline manganites have been studied. We find that the Ti-dopant causes the melting of the charge ordering state and the presence of the short-range antiferromagnetic phase. The electron-spin resonance spectra and M(H) hysteresis loops reveal that the antiferromagnetic coupling is weakened rather than strengthened upon temperature decreases. The short-range antiferromagnetic phase is metastable and transforms into the stable ferromagnetic state.

Cubic helimagnet FeGe has emerged as a class of skyrmion materials near room temperature that may impact future information technology. Experimentally identifying the detailed properties of skyrmion materials enables their practical application acceleratedly. Here we study the magnetic entropy change (MEC) of single-crystalline FeGe in its precursor region and clarify its close relation to the critical exponents of a second-order phase transition in this area. The maximum MEC is found to be 2.86 J/kg K for a 7.0 T magnetic-field change smaller than that of common magnetocaloric materials indicating the multiplicity and complexity of the magnetic structure phases in the precursor region. This result also implies that the competition among the multimagnetic phases can partly counteract the magnetic-field–driven force and establishes a stable balance. Based on the obtained MEC and the critical exponents, the exact Curie temperature of single-crystalline FeGe under zero magnetic field is confirmed to be 279.1 K, higher than the previously reported 278.2 K. This finding paves the way for reconstruction of the FeGe phase diagram in the precursor region.

Dimensionality is one of the most important parameters in the determination of the physical properties. Therefore, tuning of effective dimensionality is of significant importance for modulating the functionality of materials. In this work, we find that the spin-dimensionality can be changed by Co-doping in the Fe1−x Co x Si system. Investigation of the critical behavior shows that the effective critical exponents for x = 0.3 agree with the three-dimensional (3D) Heisenberg model with (d is the spatial-dimensionality, and n is the spin-dimensionality). With the increase of Co-content, the effective critical exponents for x = 0.5 fulfill the 3D-XY model with , while those for x = 0.6 approach the 3D-Ising model with . These results indicate the lowering of the spin-dimensionality with the increase of Co-content in Fe1−x Co x Si. We suggest that the modulation of the spin-dimensionality in Fe1−x Co x Si should result from the enhancement of the anisotropic magnetic interaction induced by the doping of Co.

The critical behavior of perovskite manganite Nd0.55Sr0.45MnO3 has been investigated based on the static magnetization measurement around the paramagnetic-ferromagnetic transition temperature 273 K. A large critical exponent and a small one have been obtained by calculating the magnetic-field dependence of the magnetic-entropy change and the Widom scaling relation. These critical exponents not only obey the scaling hypothesis, but also corroborate the results obtained from the Kouvel-Fisher method. In comparison with the values given by standard models, these obtained exponents are very close to those expected from the mean-field model ( and ) and its magnetic-coupling type belongs to nearly long-range interaction. We suggest that the A-site spin disorder and localized magnetic phase competition are the main reasons for the actual critical exponents to show a slight deviation from the theoretical model.

The critical properties of the ferromagnet CdCr2Se4 around the paramagnetic-ferromagnetic phase transition have been investigated. It is found that the 3D-Heisenberg model is the best one to describe the critical phenomena around the critical point. Critical exponents β=0.337±0.03 and γ=1.296±0.109 at TC=130.48±0.34 are obtained. In addition, the critical exponent δ=4.761±0.129 is determined separately from the isothermal magnetization at TC. These critical exponents fulfill the Widom scaling relation δ=1+γ/β. Based on these critical exponents, the magnetization-field-temperature (M-H-T) data around TC collapses into two curves obeying the single scaling equation M(H, e)=eβf±(H/eβ+γ). Although the 3D-Heisenberg model is the most satisfactory model to describe this system, critical exponents for CdCr2Se4 are slightly smaller than the theoretical exponents (β=0.36, γ=1.39 and δ=4.8). This indicates that the exchange interaction J(r) decays slower than r− 5 in this system, which can be attributed to the spin-lattice coupling.

In this paper, we report unusual thermal hysteresis behaviour in half-doped manganites Nd0.5Sr0.5−xCaxMnO3 (0.0 ≤ x ≤ 0.50). For 0.05 ≤ x < 0.25 samples, the magnetization curves show a counterclockwise hysteresis loop. For 0.25 < x ≤ 0.40 samples, however, they exhibit a clockwise loop. The inverse hysteretic behaviour stems from the competition between two kinds of strain, namely, the compressive strain and the tensile strain. The former produces a counterclockwise thermal hysteresis while the latter leads to a clockwise one. In the meantime, a magnetic instability is observed and the strain relaxation should be the main reason for it.

The electrical and magnetic properties of Ln0.4Ca0.6MnO3 compositions (Ln = La, Pr, Nd, Sm) have been investigated. The effect of on the charge-ordering behavior of the manganites is considered to be profound. The charge-ordering temperature TCO increases with decreasing , the antiferromagnetic charge-ordering state transforms from long-range into local short-range ordering and the magnetic behaviors for Ln = La, Pr, Nd, Sm are all different. Through the M–T, M–H, and electron spin resonance measurements, it is found that the magnetization in M–T curves comes from the paramagnetic contribution of disordered Mn ions at the B-site and magnetic ions at the A-site. The rise of TCO is attributed to the fact that eg electrons are localized by decreasing , and the different behavior of M–T curves below TCO originates from the number of remaining spin disordered Mn ions after the formation of the charge-ordering phase in the manganites.