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• (Mn 2 Sb) 1- x Bi x single crystals were batch-grown by an improved Bridgeman method. • Substitution of Sb by Bi leads to a shrinkage of cell volume and occurrence of the first-order transition. • Effects of chemical doping and hydrostatic pressure application were compared for the crystal with x = 0.12. • Large magnetoresistance and magnetostrain with good reversibility were attained at 120 K under 30 kOe for x = 0.12. We investigate the effects of Bi substitution on the structure, magnetization, magnetoresistance, and magnetostrain in single crystals of (Mn 2 Sb) 1- x Bi x (x = 0.06, 0.08, 0.1, and 0.12). It is found that the element Bi can be partially substituted for Sb in the tetragonal Mn 2 Sb main phase, and partially forms the MnBi and Bi-rich secondary phases. The introduction of Bi causes the simultaneous lattice shrinkages in a and c for the main phase, and also enhances the transition temperature of the first-order magnetoelastic ferrimagnetic-antiferromagnetic transition. Such an enhancement in transition temperature due to contraction of the unit-cell volume contraction is also experimentally proven based on the thermomagnetic curves under hydrostatic pressure for a crystal with × = 0.12. The volume contraction rate due to hydrostatic pressure is deduced to be −0.0386 Å3/GPa. Moreover, the highest values of in-plane magnetoresistance (∼-30%) and magnetostrain (∼−1448 ppm) with good reversibility are attained at 120 K under 30 kOe, which was proven to be the optimal magnetic field. Our experimental results show that Mn 2 Sb-based intermetallic compounds can be considered promising candidates for low-cost, multifunctional magnetic materials. [ABSTRACT FROM AUTHOR]

An experimental investigation was conducted to understand the influence of hydrostatic pressure on phase transition, thermal expansion and barocaloric property of a polycrystalline Ni 54 Mn 23 Ga 23 alloy. Two pressure ranges of 0–1.28 GPa and 0–0.74 GPa were selected for thermal expansion and barocaloric property measurements due to the different test limits of instrumentals. The pressure dependence of fourteen parameters was studied systematically. It was found that the sample experiences a martensitic transformation (MT) near room temperature and the response of MT peak temperature (T M) to pressure is about 15.89 K/GPa. The phase transition strain (λ tr), transformation width (Δ T tr) relative volume change (|Δ V / V |) and maximum adiabatic temperature change (Δ T ad) max increase linearly with pressure and their shifting rates are about 0.071 %/GPa, 7.5 K/GPa, 0.211 %/GPa and 12.2 K/GPa, respectively. Simultaneously, applying hydrostatic pressure can also enhance the barocaloric property of the sample, leading to a large increase in the absolute value of the maximum entropy change (|Δ S | max), the refrigerating capacity (RC) and their reversible values. On cooling, the sensitivities of the reversible RC and its proportion to pressure are around 185.52 J/kg GPa and 16.7 %/GPa, respectively. Finally, the average linear expansion coefficient (α ave) of both martensite and austenite phases keeps unchanged while in the MT region it decreases from -99.84×10–6/K to -86.04×10–6/K with increasing pressure from 0 to 1.28 GPa. These findings indicate that applying hydrostatic pressure can effectively adjust the phase transformation, thermal expansion and barocaloric property of Ni-Mn-Ga alloys, which are meaningful for their application in solid-state refrigeration. • Pressure can effectively adjust phase transformation, thermal expansion and barocaloric property of Ni 54 Mn 23 Ga 23 alloy. • A large response of martensitic transformation (MT) peak temperature to pressure is reported. • The barocaloric property and its reversibility are highly sensitive to pressure. • The average linear expansion coefficient during MT decreases with increasing pressure. [ABSTRACT FROM AUTHOR]

• Applying hydrostatic pressure can push the MT to a higher temperature. • Curie transition almost remains unchanged under hydrostatic pressure. • The average magnetic moment and mass susceptibility of SPM cluster are reduced. • The strength of FM/AFM interactions are suppressed by hydrostatic pressure. • The application of hydrostatic pressure suppresses the exchange bias effect. The effect of hydrostatic pressure on martensitic transformation (MT), superparamagnetic (SPM) and exchange bias (EB) behaviors in polycrystalline Ni 45 Cu 5 Mn 35 In 15 has been intensively investigated by various experimental methods. The experimental results show that the studied alloy experiences a MT from the austenitic state with a L 2 1 -type cubic structure to the martensitic state with a seven-layer (7 M) modulated orthorhombic structure with decreasing temperature, accompanied by a significant change in magnetization. It is found that applying hydrostatic pressure can induce the MT to occur in the higher temperature, while the Curie transition almost remains unchanged due to the suppression of ferromagnetic (FM) coupling. In addition, the applied hydrostatic pressure can suppress the EB field and coercivity of the studied alloy due to the reduction of the competition between FM and AFM interactions. This phenomenon can be attributed to the fact that the application of hydrostatic pressure reduces the size of the SPM cluster and its average magnetic moment. [ABSTRACT FROM AUTHOR]

Both the barocaloric effect (BCE) and its reversible behavior during martensitic transformation (MT) have been experimentally investigated in Ni 42.3 Co 7.9 Mn 38.8 Sn 11 quaternary Heusler alloy. The experimental results show that the studied alloy experiences the MT from the ferromagnetic L 2 1 -type cubic structure to the paramagnetic-like three-layered (3 M ) modulated monoclinic structure, resulting in a value of ∼1.1% for the relative volume change ε between two phases. Due to appearance of an enhanced ε , the migration rate of martensitic transformation with respect to the hydrostatic pressure reaches ∼4.7 K/kbar, while a high transition entropy change (∼28 J/kg K) is still maintained. Based on an indirectly estimated method, the calculated maximum value for isothermal entropy change Δ S T achieves ∼ -23 J/kg K with the pressure change of 6.2 kbar, which yields the values of ∼10 K for adiabatic temperature change Δ T a d and ∼786 J/kg for relative cooling power (RCP), performing a large BCE. According to the change of phase fraction at selected hydrostatic pressures, a detailed schematic diagram has been established to evaluate the reversibility of this effect. With applying an external cyclic pressure of 6.2 kbar, the maximum repeatable values calculated for both Δ S T and Δ T a d are decreased to ∼ -15 J/kg K and ∼5 K, respectively. This is attributed to an insufficient driving force, which can only partially transform this material, leading to a reversible MT appeared in the mixed state. [ABSTRACT FROM AUTHOR]

We report effect of hydrostatic pressure on martensitic transformation in polycrystalline Ni 44.6 Co 5.5 Mn 35.5 In 14.4 . With applying pressure, the transformation moves to high temperatures at a rate of 4.4 K/kbar. Utilizing an indirect method, the calculated maximum isothermal entropy changes achieve ~ 14.3 J/kg K at 2.76 kbar and ~ 15.6 J/kg K at 5.98 kbar, which respectively output the values of ~ 5 K and ~ 6 K for the adiabatic temperature change near room temperature. After deducting the average hysteretic loss (~ 152 J/kg), the effective refrigeration capacities still reach ~ 38 J/kg at 2.76 kbar and ~ 247 J/kg at 5.98 kbar, performing an enhanced barocaloric effect. [ABSTRACT FROM AUTHOR]

The influence of isotropic physical pressure, applied either during the high-pressure-high-temperature (HPHT) annealing or the measuring processes, on the magnetic properties of NdFeO 3 single crystal, has been investigated. In comparison to the complete spin reorientation (SR) in an as-grown NdFeO 3 single crystal, the thermomagnetic M (T) and isothermal M (H) curves for a HPHT-annealed sample indicates an incomplete SR transition from a Γ 2 -rich to a Γ 4 -rich Γ 24 mixed phase. Moreover, the M (T) curves of the as-grown sample under different measuring hydrostatic pressures suggest that the SR transition takes place in the sequence of Γ 2 → Γ 1 + Γ 2 + Γ 4 → Γ 1 + Γ 4 → Γ 4 , instead of the Γ 2 → Γ 2 + Γ 4 → Γ 4, without applying pressure during the measuring process. Such manipulation of the magnetic configuration reveals that the 3 d -4 f interaction in the NdFeO 3 could be greatly affected by the isotropic pressure. These findings may provide a new perspective and possibility for the tuning of the magnetism and corresponding microscopic interactions. • A comparative study of isotropic pressure on NdFeO3 single crystal is carried out. • High-pressure-high-temperature annealing leads to an incomplete spin reorientation • Hydrostatic pressure in the measuring process introduces an intermediate phase. • Isotropic pressure can tune the magnetism and microscopic interactions in NdFeO3. [ABSTRACT FROM AUTHOR]

The evolutions of electrical transport property and Baroresistance (BR) effect at the martensitic transformation (MT) with the change of Co content have been systematically investigated in the Ni 50- x Co x Mn 35 In 15 (0 ≤ x ≤ 7) Heusler system. The structure measurements show that every sample undergoes first-order MT from a L 2 1 cubic structure to a 3 M monoclinic structure. According to magnetic measurements, it is also found that the samples with lower Co content (0 ≤ x ≤ 3) exhibit a paramagnetic MT, i.e. the MT occurs between the paramagnetic austenite and the paramagnetic martensite. At higher Co content, however, the samples display a metamagnetic MT, i.e. the MT occurs between the ferromagnetic austenite and the paramagnetic martensite. Due to the enhancement of the ferromagnetic ordering for the austenitic phase with Co increasing, the difference in resistivity between austenitic and martensitic phases is enlarged significantly. This leads to a giant BR effect with a value of ∼250% associated with the hydrostatic pressure-induced MT can be observed in the sample with x = 6. Moreover, the Hall measurement results indicate that the difference in electrical transport behavior between both phases for the studied alloys mostly relies on the mobility of carriers related to the electro-lattice and the electro-spin scatterings. In this case, the underlying mechanism of the relative contributions originating from these two different scattering processes to the saturated BR effect has been separated quantitively based on the electrical transport measurements under applied different hydrostatic pressures. It demonstrates that the electron-spin scattering acts as a dominant role in improvement of the BR effect for this system. • The MT from a paramagnetic type into a metamagnetic one has been found. • A giant BR effect (∼250%) has been obtained around the room temperature. • The change of electrical transport during MT depends on the mobility of carriers. • Both electro-lattice and electro-spin scatterings has been separated quantitively. • The spin-dependent scattering plays a crucial role to improve the BR effect. [ABSTRACT FROM AUTHOR]

• Spin reorientation vanishes at a high magnetic field for a TmFeO 3 single crystal. • Evidence of magneto-structural coupling in the TmFeO 3 single crystal is provided. • Spin reorientation shifts and widens under hydrostatic pressure. • Widening of spin reorientation transition is attributed to an intermediate phase. We report the growth of a TmFeO 3 single crystal, its magnetic and structural properties upon varying temperature, magnetic field, and hydrostatic pressure. The abrupt change related to the spin reorientation (SR) process vanishes under a 30 kOe magnetic field in both thermomagnetic and strain curves, indicating strong magneto-structural coupling in such orthoferrite. Interestingly, the thermomagnetic curve under hydrostatic pressure reveals that the SR shifts towards higher temperatures and its temperature interval widens upon the application of external hydrostatic pressure. Combining the strain data obtained under similar conditions, the onset temperature shift of SR is concluded to originate from changes in structural parameters and widening of the SR transition is attributed to the presence of an intermediate phase. These findings may shed light on the envisage of potential uses in magneto-mechanical and transducer devices, based on the interaction between structure and magnetism. [ABSTRACT FROM AUTHOR]

The structure, transition properties, and hydrostatic pressure (p) and magnetic field (B) dependence of transition temperatures and operation-temperature window (Δ T , defined as the temperature range of martensitic transition) were investigated in Ni 53 Mn 21 Ga 26 alloy. The results reveal that all the transition temperatures and Δ T increase almost linearly with increasing magnetic field and pressure. Particularly, a stronger dependence of peak temperature (T M) and Δ T on pressure, d T M /d p = 25.7 K/GPa and dΔ T /d p = 18.7–22.7 K/GPa, is observed in contrast with the smaller values of d T M /d B = 1.3 K/T and dΔ T /d B = 1.4–1.7 K/T found in Ni 53 Mn 21 Ga 26 alloy. Furthermore, the value of 25.7 K/GPa may be the largest shift in T M with pressure observed in polycrystalline Ni–Mn-Ga systems. Clearly, the sensitivities of T M and Δ T to pressure are much higher than those to magnetic field. These findings illustrate that applying hydrostatic pressure is beneficial to broaden Δ T in Ni 53 Mn 21 Ga 26 alloy. • Ni 53 Mn 21 Ga 26 alloy exhibits a magnetostructural transformation (MST). • Hydrostatic pressure effects on the phase transition properties and operation-temperature window (Δ T) have been studied. • A large shift in peak temperature with pressure of 25.7 K/GPa was observed. • A strong response of Δ T to pressure p , dΔ T /d p = 18.7–22.7 K/GPa, was reported. • Hydrostatic pressure can effectively broaden the operation-temperature window. [ABSTRACT FROM AUTHOR]

The structural, magnetic, magnetocaloric and barocaloric properties were investigated in Ni 55.5 Mn 17.8 Ga 26.7 alloy. The results show that the sample experiences two successive magnetostructural transformations (MSTs) with decreasing/increasing temperature. The field-induced entropy change and pressure-induced entropy change are only −7.55 J/kg K for a field change of Δ H = 3 T and −10.52 J/kg K for a pressure change of Δ P = 0.622 GPa while the corresponding refrigeration capacity (RC) achieves 68.80 J/kg and 247.83 J/kg, respectively. Such considerable RC values can be ascribed to the broadening of the full-width at half maximum (FWHM) due to the two successive MSTs. It was observed that RC and FWHM increase with magnetic field and pressure, which results in an enhancement of magnetocaloric and barocaloric effects. Importantly, RC and FWHM under Δ P = 0.622 GPa are comparable to and even larger than those reported in some expensive rare-earth-based magnetic refrigerants. The responses of RC and FWHM to pressure are 89.05 J/kg GPa and 4.77 K/GPa for 0 ≤ P ≤ 0.3 GPa and the values are 654.57 J/kg GPa and 73.86 K/GPa for 0.3 ≤ P ≤ 0.622 GPa. The FWHMs of 11.23 K under Δ H = 3 T and of 32.83 K under Δ P = 0.622 GPa are obtained. All these excellent properties originated from two successive MSTs would make Ni 55.5 Mn 17.8 Ga 26.7 alloy promising as a new and inexpensive multicaloric material used in the solid refrigeration technology. • Ni 55.5 Mn 17.8 Ga 26.7 alloy exhibits two successive magnetostructural transformations (MSTs). • Large magnetocaloric and barocaloric effects were observed due to the two successive MSTs. • Two successive MSTs and hydrostatic pressure can effectively broaden the phase transforming temperature span. • A large refrigerant capacity of 247.83 J/kg was obtained under a pressure change of 0.622 GPa. • An inexpensive multicaloric material Ni 55.5 Mn 17.8 Ga 26.7 alloy was reported. [ABSTRACT FROM AUTHOR]

The crystal structure, transformation property and magnetocaloric effect (MCE) were investigated in Ni 55.5 Mn 17.8 Ga 26.7 alloy. The sample at room temperature exhibits an unmodulated martensitic structure with a small residual trace of 7 M modulated martensitic structure. Two successive magneto-structural transformations (MSTs) consisting of martensitic and intermartensitic transformations are observed. It is found that the maximum isothermal entropy change |Δ S | max of 7.65 J/kg K at 309 K and refrigeration capacity (RC) of 78.84 J/kg are attained for a field change μ 0 Δ H = 3 T under ambient pressure (p = 0 GPa). The enhanced MCE can be ascribed to the two successive MSTs. Much importantly, the |Δ S | max is basically independent of hydrostatic pressure and equals to 7.74 J/kg K at 314 K for p = 0.622 GPa. Besides, the application of hydrostatic pressure improve the width of phase transition and a large RC of 101.57 J/kg has been observed for p = 0.622 GPa under μ 0 Δ H = 3 T. Consequently, the response of RC to magnetic field increases from 26.86 J/kg T for p = 0 GPa to 34.13 J/kg T for p = 0.622 GPa. The reversible RC is also improved by pressure. Such an enhanced MCE and the non-toxic raw materials make this alloy particularly appealing for solid-state cooling technologies. • Ni 55.5 Mn 17.8 Ga 26.7 alloy exhibits two successive magneto-structural transformations. • An enhanced MCE associated with the two successive MSTs was obtained. • The maximum isothermal entropy change almost keeps constant under ambient and high pressures. • Application of hydrostatic pressure can effectively broaden the phase transforming temperature span. • A considerable refrigerant capacity was obtained under hydrostatic pressure. [ABSTRACT FROM AUTHOR]