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Searching for novel ferromagnetic oxides with high Curie temperature (TC) has been one of the main goals for oxide spintronics. The well-known perovskite cobaltate LaCoO3 is a classical ferromagnet in its thin-film form; however, it suffers from a low TC (∼ 85 K). Here we report a new type of ferromagnetic La-Co-O films with an ultrahigh TC of ∼ 820 K. They are fabricated by pulsed laser deposition from a LaCoO3 target at low oxygen partial pressures. Detailed structural analysis indicates that they crystallize in terms of the Ruddlesden–Popper phase of La2CoO4±x. In sharp contrast to the antiferromagnetism of bulk La2CoO4, the strong ferromagnetism in the La2CoO4±x thin films is firmly demonstrated by magnetometry measurements, X-ray magnetic circular dichroism characterization, and magnetotransport experiments. More importantly, density functional theory calculations indicate that the nonstoichiometric oxygen induces an antiferromagnetic-to-ferromagnetic phase transition, accompanied by the orbital reconstruction of Co 3d electrons. Thus, our study provides an attractive strategy for designing or synthesizing exotic magnetic oxides with high ordering temperatures. [ABSTRACT FROM AUTHOR]

Due to the strong interactions from multiple degrees of freedom at the interfaces, electron-correlated oxide heterostructures have provided a promising platform for creating exotic quantum states. Understanding and controlling the coupling effects at the oxide interface are prerequisites for designing emergent interfacial phases with desired functionalities. Here, we report the dimensional control of the interface coupling-induced ferromagnetic (FM) phase in perovskite-CaRuO3/infinite-layered-SrCuO2 superlattices. Structural analysis reveals the occurrence of chain-type to planar-type structural transitions for the SrCuO2 layer as the layer thickness increases. The Hall and magnetoresistance measurements indicate the appearance of an interfacial FM state in the originally paramagnetic CaRuO3 layers when the CaRuO3 layer is in proximity to the chain-type SrCuO2 layers; this superlattice has the highest Curie temperature of ~75 K and perpendicular magnetic anisotropy. Along with the thickness-driven structural transition of the SrCuO2 layers, the interfacial FM order gradually deteriorates and finally disappears. As shown by the X-ray absorption results, the charge transfer at the CaRuO3/chain-SrCuO2 and CaRuO3/plane-SrCuO2 interfaces are different, resulting in dimensional control of the interfacial magnetic state. The results from our study can be used to facilitate a new method to manipulate interface coupling and create emergent interfacial phases in oxide heterostructures. Harnessing Quantum States: A Breakthrough in Oxide Heterostructures Perovskite transition-metal oxides, known for their complex electron interactions, exhibit unique physical properties like superconductivity and magnetoresistance. However, layering these materials can result in new, unexpected behaviors at their interfaces. This study focuses on a layered structure of perovskite ruthenate and strontium cuprate. The research shows that by controlling the thickness of SCO layers in CRO/SCO superlattices, it is possible to induce ferromagnetism in CRO, which normally does not exhibit this property. The authors conclude that this manipulation of interface coupling can lead to new interfacial phases with potential applications in spintronics. The findings open up possibilities for future research into the control of quantum phases in complex oxide materials. This summary was initially drafted using artificial intelligence, then revised and fact-checked by the author. In this paper, we report the dimensional control of the interface coupling-induced ferromagnetic phase in perovskite-CaRuO3/infinite-layered-SrCuO2 superlattices. The Hall and magnetoresistance measurements indicate the appearance of an interfacial ferromagnetic state in the originally paramagnetic CaRuO3 layers when the CaRuO3 layer is in proximity to the chain-type SrCuO2 layers; this superlattice has the highest Curie temperature of ~75 K and perpendicular magnetic anisotropy. Along with the thickness-driven structural transition from chain-type to planar-type of the SrCuO2 layers, the interfacial ferromagnetic order gradually deteriorates and finally disappears. [ABSTRACT FROM AUTHOR]

The promotion of innovation by the market transaction mechanism is affected by the perfection of the market system, the support of government policies, and companies' operational strategies. However, few empirical studies explore this subject. In this context, we investigated how China's carbon emission trading (CET) policy promotes companies' total factor productivity (TFP) from the perspective of operational strategies, technological innovation, and market environment. Using the micro-data of listed companies from the Chinese stock "A" markets, we employed the difference-in-differences method to identify the CET policy's effect on companies' TFP. The benchmark regression results reveal that the policy has significantly boosted companies' TFP. Furthermore, the mechanism analysis shows that companies could enhance their TFP by promoting technological innovation instead of operational strategies. Meanwhile, the government can facilitate this improvement effect by optimizing the market environment. Moreover, the heterogeneity analysis of market failure demonstrated that it would affect the performance of the CET mechanism. Additionally, the CET scheme's effect on companies' TFP is heterogeneous in terms of industry, ownership, and region. The results suggest that the Chinese government should continue to improve the market and institutional systems, increase R&D technology subsidies for innovation activities, and enhance the level of financial development. [ABSTRACT FROM AUTHOR]

Low grade waste heat accounts for ~65% of total waste heat, but conventional waste heat recovery technology exhibits low conversion efficiency for low grade waste heat recovery. Hence, we designed a thermomagnetic generator for such applications. Unlike its usual role as the coil core or big magnetic yoke in previous works, here the magnetocaloric material acts as a switch that controls the magnetic circuit. This makes it not only have the advantage of flux reversal of the pretzel-like topology, but also present a simpler design, lower magnetic stray field, and higher performance by using less magnetocaloric material than preceding devices. The effects of key structural and system parameters were studied through a combination of experiments and finite element simulations. The optimized max power density PDmax produced by our device is significantly higher than those of other existing active thermomagnetic, thermo, and pyroelectric generators. Such high performance shows the effectiveness of our topology design of magnetic circuit with magnetocaloric switch. The utilization of waste heat is an important way of combining energy saving to emission reductions. Here, authors demonstrate a magnetocaloric material as a controlling switch in a thermomagnetic generator for waste heat recovery. [ABSTRACT FROM AUTHOR]

Solid state refrigeration based on caloric effect is regarded as a potential candidate for replacing vapor-compression refrigeration. Numerous methods have been proposed to optimize the refrigeration properties of caloric materials, of which single field tuning as a relatively simple way has been systemically studied. However, single field tuning with few tunable parameters usually obtains an excellent performance in one specific aspect at the cost of worsening the performance in other aspects, like attaining a large caloric effect with narrowing the transition temperature range and introducing hysteresis. Because of the shortcomings of the caloric effect driven by a single field, multifield tuning on multicaloric materials that have a coupling between different ferro-orders came into view. This review mainly focuses on recent studies that apply this method to improve the cooling performance of materials, consisting of enlarging caloric effects, reducing hysteresis losses, adjusting transition temperatures, and widening transition temperature spans, which indicate that further progress can be made in the application of this method. Furthermore, research on the sign of lattice and spin contributions to the magnetocaloric effect found new phonon evolution mechanisms, calling for more attention on multicaloric effects. Other progress including improving cyclability of FeRh alloys by introducing second phases and realizing a large reversible barocaloric effect by hybridizing carbon chains and inorganic groups is described in brief. [ABSTRACT FROM AUTHOR]

The barocaloric effect (BCE) has emerged as an intense research topic in regard to efficient and clean solid-state refrigeration. Materials with solid-liquid phase transitions (SL-PTs) usually show huge melting entropies but cannot work in full solid-state refrigeration. Here, we report a colossal barocaloric effect realized by exploiting high entropy inherited from huge disorder of liquid phase in amorphous polyethylene glycol (PEG), which is solidified by introducing 5 wt.% polyethylene terephthalate (PET). Transmission electron microscopy (TEM) combined with X-ray diffraction (XRD) demonstrates the amorphous nature of the high-temperature phase after fixation by PET. Although PEG loses its –OH end mobility in amorphous solid, high entropy still retains owing to the retained high degrees of freedom of its molecular chains. The remaining entropy of amorphous PEG is up to 83% of that of liquid PEG in PEG10000/PET15000, and the barocaloric entropy change reaches ΔSp ∼ 416 J·kg−1·K−1 under a low pressure of 0.1 GPa, which exceeds the performance of most other BCE materials. Infrared spectra combined with density function theory (DFT) calculations disclose conformational change from the liquid to amorphous state, which explains the origin of the large entropy retained and hence the colossal BCE of the solidified PEG. This research opens a new avenue for exploring full solid-state barocaloric materials by utilizing genetic high entropy from huge disordering of liquid phases in various materials with SL-PTs. Refrigeration: Phasing out freon with flexible plastics A technique that turns liquid polymers used in medicine and industry into solid-state refrigerants could lower demand for hydrofluorocarbon-based coolants. Recent studies have shown that plastics which undergo energy-absorbing structural phase transitions in response to mechanical pressure show promise as non-toxic refrigerants. Zibing Yu from the Chinese Academy of Sciences, Beijing, and colleagues now describe a method for creating plastic refrigerants with polyethylene glycol (PEG), an inexpensive polymer used to stabilize substances ranging from laxatives to toothpaste. By adding a small proportion of an aromatic polyester to a solution of PEG, the team created a solid composite with an exterior stabilized by hydrogen bonds and an interior containing flexible hydrocarbon chains. The new composite's liquid-like center offered similar amounts of solid-state cooling to contemporary plastic refrigerants and potentially low manufacturing costs. A new type of solid-sate colossal barocaloric material was fabricated by exploiting the amorphous high entropy inherited from huge disorder of liquid phase in solidified PEG(HO(CH2CH2O)nH) by introducing 5 wt.% PET((C10H8O4)m) for copolymerization. Although PEG loses –OH end mobility, high entropy still retains in amorphous solid. Consequently, a colossal barocaloric entropy change as high as ΔSp ∼ 416 J·kg−1·K−1 under a low pressure of 0.1 GPa was demonstrated. [ABSTRACT FROM AUTHOR]

Barocaloric materials are particularly promising for green and efficient solid-state cooling technology because of their great potential in terms of cooling performance. However, intermetallic materials with outstanding barocaloric effects under low hydrostatic pressure are especially lacking, which has severely delayed the development of barocaloric refrigeration. Here, in a rare-earth intermetallic La-Ce-Fe-Si-H, we achieve a giant specific barocaloric temperature change of 8 K per kbar according to direct measurements of the adiabatic temperature change ΔTBCE under hydrostatic pressure, which is confirmed by a phenomenological transition simulation. This barocaloric strength is significantly better than those in previously reported phase-transitioned alloys. By using a cutting-edge in situ neutron diffraction technique operating under simultaneously varying temperature, magnetic field, and hydrostatic pressure, we reveal that the large isotropic transition volume change in La-Ce-Fe-Si-H plays a crucial role in the giant barocaloric effect. Additionally, we employ Landau expansion theory to demonstrate that the high sensitivity of the transition temperature to the applied pressure produces the sizable ΔTBCE in the itinerant electron metamagnetic transition alloys. Our results provide insight into the development of high-performance barocaloric materials and related cooling systems.A rare-earth intermetallic La-Ce-Fe-Si-H has been directly measured to cool 8 K when it is under a 1 kbar pressure. This barocaloric strength significantly outperforms those in previously reported phase-transitioned alloys. A multifield-dependent neutron diffraction has revealed that the large isotropic transition volume change for La-Ce-Fe-Si-H plays a crucial role in exploring the giant barocaloric effect. [ABSTRACT FROM AUTHOR]

'Magic-angled' structure currently attracts increasing attention from condensed matter physics due to its amazing performance in superconductivity of graphene. The similar pattern formation of nanoparticles will bring about novel physics in nanoscale that causes the next generation nanodevices. However, it remains a challenging task to acquire such patterns by self-assembly process. In this article, we reported a Moiré interference pattern formation of magnetic nanoparticles regulated by a rotational magnetic field. The colloidal concentration, the strength, and the frequency of magnetic field were found to affect the pattern formation. The mechanism lied in a two-step process. First, the magnetic nanoparticles formed bilayers of superlattice driven by hydrophobic interaction of interfacial self-assembly. Then, the bilayers of superlattice yielded asynchronous rotational displacement resulting from the magnetic force so that the Moiré interference pattern of nanoparticles formed. This fabrication methodology based on the field-controlled self-assembly provided a novel and simple means to get 'magic angled' structures in nanoscale that will enrich the physical understanding of nanotechnology. [ABSTRACT FROM AUTHOR]

The 2:14:1-type rare-earth (RE)-Fe-B permanent magnets prepared by the dual alloy method have been found to possess much superior magnetic properties to those prepared by the single alloy method, providing an appealing route to promote the utilization of high-abundance RE elements Ce and La and balance the use of the RE source. However, the relationship between magnetic interactions among different 2:14:1 main phases and superior magnetic properties is still unclear. In this study, we investigated the magnetic interactions and reversal field distribution in these magnets using first-order reversal curve (FORC) images. The FORC images showed that (Nd, Pr)27.8(La, Ce)2.7FebalM1.4B1.0 (S-9) and (Nd, Pr)19.5(La, Ce)11.0FebalM1.4B1.0 (S-36) have the characteristics of multiple main phases. The reverse magnetic fields corresponding to the soft and hard main phases, as well as the associated exchange coupling, were highly dependent on the LaCe content. The higher the LaCe content, the weaker the exchange coupling and the more asynchronous the demagnetization process. In addition, the FORC images indicated that the magnetization reversal process also varies with LaCe content, where the nucleation and propagation of reversed domains dominant in the S-9 magnet, while the domain propagation in the S-36 magnet is considerably suppressed. Additional micro-magnetic simulations also revealed that the coercivity and exchange coupling of multi-main-phase magnets decrease with increasing LaCe content, correlating well with the experimental results. These findings may not only contribute to a better understanding of the complex magnetic interactions between the soft and hard phases and how they affect macroscopic magnetic properties but also help in improving the magnetic performance of the RE-Fe-B magnets with high LaCe content. [ABSTRACT FROM AUTHOR]

Multistate magnetic memory effect in heterostructures composed of FeRh thin films with antiferromagnetic (AFM)-ferromagnetic (FM) phase transition and (001)-oriented PMN-PT substrates has been investigated. Utilizing a unipolar electric field, the nonvolatile change in magnetization was nearly doubled compared with that obtained utilizing a conventional bipolar bias. Four stable nonvolatile magnetic states were obtained over a broad temperature span, from 320 to 390 K, by adjusting the amplitude of the unipolar electric pulses, demonstrating the possibility of realizing a multistate nonvolatile magnetic memory in the FeRh/PMN-PT heterostructures. This work provides a new strategy for enhancing the magnetic response by utilizing unipolar electric fields and promotes the utilization of AFM-FM phase transition materials in multifunctional information storage and novel spintronic devices. [ABSTRACT FROM AUTHOR]

Solid-state refrigeration based on the caloric effect is viewed as a promising efficient and clean refrigeration technology. Barocaloric materials were developed rapidly but have since encountered a general obstacle: the prominent caloric effect cannot be utilized reversibly under moderate pressure. Here, we report a mechanism of an emergent large, reversible barocaloric effect (BCE) under low pressure in the hybrid organic–inorganic layered perovskite (CH3–(CH2)n−1–NH3)2MnCl4 (n = 9,10), which show the reversible barocaloric entropy change as high as ΔSr ∼ 218, 230 J kg−1 K−1 at 0.08 GPa around the transition temperature (Ts ∼ 294, 311.5 K). To reveal the mechanism, single-crystal (CH3–(CH2)n−1–NH3)2MnCl4 (n = 10) was successfully synthesized, and high-resolution single-crystal X-ray diffraction (SC-XRD) was carried out. Then, the underlying mechanism was determined by combining infrared (IR) spectroscopy and density function theory (DFT) calculations. The colossal reversible BCE and the very small hysteresis of 2.6 K (0.1 K/min) and 4.0 K (1 K/min) are closely related to the specific hybrid organic–inorganic structure and single-crystal nature. The drastic transformation of organic chains confined to the metallic frame from ordered rigidity to disordered flexibility is responsible for the large phase-transition entropy comparable to the melting entropy of organic chains. This study provides new insights into the design of novel barocaloric materials by utilizing the advantages of specific organic–inorganic hybrid characteristics.Solid-state coolants: Hybrid crystals deliver big chills at low pressures Materials that can absorb and release heat under low mechanical pressure hold promise for high-efficiency refrigeration technology. Recent studies have shown that significant compression-induced cooling effects at low pressures can be achieved using crystals known as perovskites containing layers of organic chains and metal cations. Yihong Gao from the Chinese Academy of Sciences in Beijing and colleagues have now uncovered the mechanism underlying the thermal response of layered perovskites. Using a combination of x-rays, spectroscopy and theoretical calculations, the team discovered how the crystal structure changes at different temperatures. Their experiments revealed a low-energy phase transition where organic chains transform from rigid states to highly flexible conformations held in place by metallic layers. The large entropy change associated with this transition and its reversible nature could aid in the design of other organic–inorganic solid-state coolants.For the emergent colossal, reversible barocaloric effect in organic–inorganic perovskite hybrids (CH3–(CH2)n−1–NH3)2MnCl4 (n = 9, 10), we successfully grew a single crystal, and the underlying mechanism was determined by high-resolution SC-XRD, IR spectroscopy and DFT calculations. The drastic transformation of organic chains confined to the metallic frame from ordered rigidity to disordered flexibility is responsible for the large phase-transition entropy, which is comparable to the melting entropy of organic chains. The result provides new insights into designing novel barocaloric materials by utilizing the disordering of organic chains of organic–inorganic hybrid materials. [ABSTRACT FROM AUTHOR]

The caloric effects under combined applications of magnetic field and hydrostatic pressure to a MnCoSi meta-magnet were investigated. Under a magnetic field change of 0–5 T, the maximum magnetic entropy change was enhanced by 35.7% when a 3.2kbar hydrostatic pressure was applied, and the cooling temperature span was extended by 60 K when a hydrostatic pressure of 9.7 kbar was applied. The coupled caloric entropy change, which originates from the coupling between the magnetism and volume, was calculated and accounted for the enhanced entropy change of MnCoSi. The present work facilitates the use of MnCoSi as a solid-state refrigerant and also enriches the investigation of the multicaloric effect under multiple external fields. [ABSTRACT FROM AUTHOR]

Topological magnetic domains exhibit many fascinating features and great potential in information storage and spintronics owing to their unique spin textures. In order to investigate the topological properties of the domain structures, the spontaneous evolutions of magnetic moments are evaluated by using Landau–Lifshitz–Gilbert equation. The equilibrium phase diagrams of the system with randomly, radial and axial distributed initial magnetic moments have been studied in detail. Simulation results show that the changes of quality factor (Q) and aspect ratio (T/D) lead to great differences in magnetization process under different initial magnetization states. Vortex, biskyrmion, skyrmion and bubble are formed as the value of Q gradually increases from 0 to 1. The system with Q < 0.5 is easy to stabilize into a vortex state, while the magnetic moments of the system with Q > 1.0 are arranged along the easy axis. When Q and T/D are in the range of 0.6 ~ 0.8 and 0.10 ~ 0.16, respectively, it is conducive to the formation of nontrivial topological domain. Biskyrmion is spontaneously formed in the system of Q = 0.6 and T/D = 0.12, proving that skyrmion-like domain can be generated in the absence of Dzyaloshinskii–Moriya interaction or external field. [ABSTRACT FROM AUTHOR]

Oxidative stress and apoptosis play critical roles in pemphigus vulgaris (PV). The main aim of the present study was to investigate the effects of RhoA/ROCK signaling on UVB-induced oxidative damage, and to delineate the molecular mechanisms involved in the UVB-mediated inflammatory and apoptotic response. In HaCaT cells, we observed that blockage of RhoA/ROCK signaling with the inhibitor CT04 or Y27632 greatly inhibited the UVB-mediated increase in intracellular reactive oxygen species (ROS). Additionally, inhibition of RhoA/ROCK signaling reduced UVB-induced apoptosis, as exemplified by a reduction in DNA fragmentation, and also elevated anti-apoptotic Bcl-2 protein, concomitant with reduced levels of pro-apoptotic protein Bax, caspase-3 cleavage and decreased PARP-1 protein. The release of inflammatory mediators TNF-α, IL-1β, and IL-6 was also attenuated. Mechanically, we observed that blockage of RhoA/ROCK repressed the TAK1/NOD2-mediated NF-κB pathway in HaCaT cells exposed to UVB. Taken together, these data reveal that RhoA/ROCK signaling is one of the regulators contributing to oxidative damage and apoptosis in human keratinocytes, suggesting that RhoA/ROCK signaling has strong potential to be used as a useful therapeutic target in skin diseases including PV. [ABSTRACT FROM AUTHOR]

La(Fe, Si)-based compounds have been considered as promising candidates for magnetic refrigerants particularly near room temperature. Herein we review recent progress particularly in the study of the effects of interstitial H and/or C atoms on the magnetic and magnetocaloric properties of La(Fe, Si) compounds. By introducing H and/or C atoms, the Curie temperature T increases notably with the increase of lattice expansion which makes the Fe 3 d band narrow and reduces the overlap of the Fe 3 d wave functions. The first-order itinerant-electron metamagnetic transition is conserved and the MCE still remains high after hydrogen absorption. In contrast, the characteristic of magnetic transition varies from first-order to second-order with the increase of C concentration, which leads to remarkable reduction of thermal and magnetic hysteresis. In addition, the introduction of interstitial C atoms promotes the formation of NaZn-type (1:13) phase in La(Fe, Si) compounds, and thus reducing the annealing time significantly from 40 days for LaFeSi to a week for LaFeSiC. The pre-occupied interstitial C atoms may depress the rate of hydrogen absorption and release, which is favorable to the accurate control of hydrogen content. It is found that the reduction of particle size would greatly depress the hysteresis loss and improve the hydrogenation process. By the incorporation of both H and C atoms, large MCE without hysteresis loss can be obtained in La(Fe, Si) compounds around room temperature, for instance, LaPrFeSiCH exhibits a large |Δ S| of 22.1 J/(kg·K) at T = 321 K without hysteresis loss for a field change of 0-5 T. [ABSTRACT FROM AUTHOR]