Low pressure reversibly driving colossal barocaloric effect in two-dimensional vdW alkylammonium halides.

Plastic crystals as barocaloric materials exhibit the large entropy change rivalling freon, however, the limited pressure-sensitivity and large hysteresis of phase transition hinder the colossal barocaloric effect accomplished reversibly at low pressure. Here we report reversible colossal barocaloric effect at low pressure in two-dimensional van-der-Waals alkylammonium halides. Via introducing long carbon chains in ammonium halide plastic crystals, two-dimensional structure forms in (CH-(CH))NHX (X: halogen element) with weak interlayer van-der-Waals force, which dictates interlayer expansion as large as 13% and consequently volume change as much as 12% during phase transition.

Electrochemical-reaction-induced synaptic plasticity in MoO-based solid state electrochemical cells.

Solid state electrochemical cells with synaptic functions have important applications in building smart-terminal networks. Here, the essential synaptic functions including potentiation and depression of synaptic weight, transition from short- to long-term plasticity, spike-rate-dependent plasticity, and spike-timing-dependent plasticity behavior were successfully realized in an Ag/MoO/fluorine-doped tin oxide (FTO) cell with continual resistance switching. The synaptic plasticity underlying these functions was controlled by tuning the excitatory post-synaptic current (EPSC) decay, which is determined by the applied voltage pulse number, width, frequency, and intervals between the pre- and post-spikes.

Ultrathin SmCo5 nanoflakes with high-coercivity prepared by solid particle (NaCl) and surfactant co-assisted ball milling.

The ultrathin SmCo5 nanoflakes with average thickness smaller than 50 nm are prepared by a novel method of solid particle (NaCl) and surfactant co-assisted ball milling. The as-prepared nanoflakes exhibit a narrower thickness distribution of 10-50 nm and high coercivity of 23 kOe. The possible formation mechanism of nanoflakes are proposed.

Moisture effects on the electrochemical reaction and resistance switching at Ag/molybdenum oxide interfaces.

An important potential application of solid state electrochemical reactions is in redox-based resistive switching memory devices. Based on the fundamental switching mechanisms, the memory has been classified into two modes, electrochemical metallization memory (ECM) and valence change memory (VCM). In this work, we have investigated a solid state electrochemical cell with a simple Ag/MoO3-x/fluorine-doped tin oxide (FTO) sandwich structure, which shows a normal ECM switching mode after an electroforming process.

Giant barocaloric effect in hexagonal Ni2In-type Mn-Co-Ge-In compounds around room temperature.

The most widespread cooling techniques based on gas compression/expansion encounter environmental problems. Thus, tremendous effort has been dedicated to develop alternative cooling technique and search for solid state materials that show large caloric effects. An application of pressure to a material can cause a change in temperature, which is called the barocaloric effect.

Strong textured SmCo5 nanoflakes with ultrahigh coercivity prepared by multistep (three steps) surfactant-assisted ball milling.

The high coercivity of 26.2 kOe for SmCo5 nanoflakes are obtained by multistep (three steps) surfactant-assisted ball milling. The magnetic properties, phase structure and morphology are studied by VSM, XRD and SEM, respectively.

Giant rotating magnetocaloric effect induced by highly texturing in polycrystalline DyNiSi compound.

Large rotating magnetocaloric effect (MCE) has been observed in some single crystals due to strong magnetocrystalline anisotropy. By utilizing the rotating MCE, a new type of rotary magnetic refrigerator can be constructed, which could be more simplified and efficient than the conventional one. However, compared with polycrystalline materials, the high cost and complexity of preparation for single crystals hinder the development of this novel magnetic refrigeration technology.

Anisotropic modulation of magnetic properties and the memory effect in a wide-band (011)-Pr0.7Sr0.3MnO3/PMN-PT heterostructure.

Memory effect of electric-field control on magnetic behavior in magnetoelectric composite heterostructures has been a topic of interest for a long time. Although the piezostrain and its transfer across the interface of ferroelectric/ferromagnetic films are known to be important in realizing magnetoelectric coupling, the underlying mechanism for nonvolatile modulation of magnetic behaviors remains a challenge. Here, we report on the electric-field control of magnetic properties in wide-band (011)-Pr0.

Giant negative thermal expansion in bonded MnCoGe-based compounds with Ni2In-type hexagonal structure.

MnCoGe-based compounds undergo a giant negative thermal expansion (NTE) during the martensitic structural transition from Ni2In-type hexagonal to TiNiSi-type orthorhombic structure. High-resolution neutron diffraction experiments revealed that the expansion of unit cell volume can be as large as ΔV/V ∼ 3.9%.

Abnormal percolative transport and colossal electroresistance induced by anisotropic strain in (011)-Pr(0.7)(Ca(0.6)Sr(0.4))(0.3)MnO₃/PMN-PT heterostructure.

Abnormal percolative transport in inhomogeneous systems has drawn increasing interests due to its deviation from the conventional percolation picture. However, its nature is still ambiguous partly due to the difficulty in obtaining controllable abnormal percolative transport behaviors. Here, we report the first observation of electric-field-controlled abnormal percolative transport in (011)-Pr(0.

Integrating giant microwave absorption with magnetic refrigeration in one multifunctional intermetallic compound of LaFe(11.6)Si(1.4)C(0.2)H(1.7).

Both microwave absorption and magnetocaloric effect (MCE) are two essential performances of magnetic materials. We observe that LaFe(11.6)Si(1.

Correlation between evolution of resistive switching and oxygen vacancy configuration in La₀.₅Ca₀.₅MnO₃ based memristive devices.

We here report a study of the correlation between the evolution of resistive switching and the oxygen vacancy configuration in La₀.₅Ca₀.₅MnO₃ (LCMO) based memristive devices.

Large improvement of coercivity in Sm-(Co,Cu)/Fe films by Cu addition.

The magnetic properties and microstructure of Sm-(Co,Cu)/Fe films were investigated systematically. The addition of Cu is helpful for keeping a better multilayer structure due to the reduction of the crystallization temperature of the hard phase. With lowering the temperature, the coercivity of the Sm-(Co,Cu)/Fe films increases rapidly with a linear relationship.

Local resistance switching at grain and grain boundary surfaces of polycrystalline tungsten oxide films.

Resistance switching behavior has been investigated in as-prepared and oxygen-annealed polycrystalline tungsten oxide films using conductive atomic force microscopy. The oxygen-annealed film appeared more insulative than the as-prepared films. The local current distributions demonstrated the lower conductivity at the grain boundaries than at the grains in the oxygen-annealed films.

Anomalously large anisotropic magnetoresistance in a perovskite manganite.

The signature of correlated electron materials (CEMs) is the coupling between spin, charge, orbital and lattice resulting in exotic functionality. This complexity is directly responsible for their tunability. We demonstrate here that the broken symmetry, through cubic to orthorhombic distortion in the lattice structure in a prototype manganite single crystal, La(0.

Magnetism, transport, and specific heat of electronically phase-separated Pr(0.7)Pb(0.3)MnO(3) single crystals.

Magnetization, resistivity, and specific heat were studied systematically in the absence and presence of magnetic field in Pr(0.7)Pb(0.3)MnO(3) single crystals, in which electronic phase separation occurs near the ferromagnetic/metallic-paramagnetic/insulating phase transition and the metal-insulator transition temperature is much higher than the Curie temperature.