Synthesis, Magnetic Properties, Magnetic Entropy and Arrot Plot of Antiferromagnetic Frustrated Er2Ti2O7 Compound

The pyrochlore $\mathrm{Er}_{2}^{3 +} \mathrm{Ti}_{2}^{4 +}\mathrm{O}_{7}^{2 -}$ was synthesized via a ceramic method using two different oxides (Er₂O₃ and TiO₂). The compound was found to crystallize in the cubic system with the $\mathrm{Fd}\overline{3}\mathrm{m}$ space group (No. 227). A magnetic study, carried out at 2 and 300 K under an applied magnetic field ?? ₀ H=0.05?T, has revealed a complex magnetic structure at low temperature. The effective paramagnetic moment $\mu_{\mathrm{eff}}^{\exp}$ , deduced from (????? ₀)^?1=f(T) curve, was found by assuming a zero moment on the transition metal atom Ti⁴⁺. The paramagnetic Curie?CWeiss temperature ?? _CW=?21.54?K, the nearest neighbor interaction J _nn =?2.30?K, the classical nearest neighbor J ^cl=?8.65?K and the dipolar D _nn =3.76?K interactions?? values have revealed an antiferromagnetic behavior for Er₂Ti₂O₇ compound at low temperature. We have also studied the effects of the magnetic field splitting of rare-earth atom Er³⁺ in the compound Er₂Ti₂O₇ curved Arrott plots.     

Investigation on Magnetic and Magnetocaloric Properties of DySe2

Journal of Superconductivity and Novel Magnetism - The magnetization measurements have been performed to bring out the magnetic and magnetocaloric properties of polycrystalline DySe2 system...     

Magnetic Properties and Magnetocaloric (MC) Effects in the Antiferromagnetic Gd2NiGa3 Compound

Journal of Superconductivity and Novel Magnetism - The magnetocaloric (MC) properties in various magnetic materials were well determined within last three decades due to its own potential...     

Structural and Magnetocaloric Properties of ErFe 2 . 4 Al 0 . 6 Compound

The structural and magnetic properties of the single-phase pseudobinary ErFe _2.4Al _0.6 compound, obtained under arc-melting conditions, have been investigated. Single crystal X-ray diffraction analysis revealed that this compound is stabilized with a hexagonal CeNi ₃-type structure (space group P6 ₃ /mmc). The partial substitution of Fe by Al in this compound occurring at all the metallic sites is reflected in the decrease of the Curie temperature Tc. Magnetization curves (2–450 K; 0–5 T) indicate a ferrimagnetic ordering with four magnetic phases induced by competitional interactions between magnetic moments of both Er and Fe. The magnetocaloric effect has been estimated from the magnetic isotherms. The relative cooling power (RCP) value indicates relatively promising magnetic refrigerant material.     

Electronic,Magnetic Properties and Magnetocaloric Effect of La2SrMn2O7 Bilayer Manganite: An Ab Initio calculations and Monte Carlo Study

Journal of Low Temperature Physics - The structure of La2SrMn2O7 (LSMO) bilayer manganite has been investigated using the Monte Carlo simulations and ab initio calculations based on the...     

Optical and Low-Temperature Magnetocaloric Properties of HoCr0.5Mn0.5O3 Compound

Journal of Superconductivity and Novel Magnetism - The optical, magnetic and magnetocaloric properties of HoCr0.5Mn0.5O3 compound have been investigated thoroughly. A multicolour photoluminescence...     

RPdAl(R=Gd-Er)的磁性和磁热效应

低温退火的LTM-RPdAl和高温退火的HTM-RPdAl分别具有正交TiNiSi型和六角ZrNiAl型结构.综述了磁场和温度变化对LTM-RPdAl和HTM-RPdAl化合物磁性和磁热效应的影响.实验结果表明,LTM-RPdAl化合物均是反铁磁性的,当R=Gd,Tb,Dy,Ho,Er时,奈尔温度TN分别为31,45,21,10和10 K.对于HTM-RPdA1化合物,当R=Tb,Ho,Er时是反铁磁性的,TN分别为43,12和5K,而当R=Gd,Dy时是铁磁性的,其居里温度分别为Tc=49,25 K.反铁磁RPdAl化合物均呈现磁场诱导的反铁磁-铁磁变磁转变.对HTM-RPdAl(R=Ho,Er)化合物,由于弱的反铁磁耦合,在低磁场下呈现出高的饱和磁化强度,从而产生大的磁热效应,在0～5 T磁场变化下的最大磁熵变值和制冷能力分别高达20.6,24.3 J/kg·K和386,299 J/kg,是优异的低温磁制冷材料.     

Electronic,Magnetic, Electric and Magnetocaloric Properties of the Multiferroic Orthorhombic YMnO3

Journal of Superconductivity and Novel Magnetism - Multiferroic oxide materials have attracted much intention in recent years due to their application in different fields such as magnetic...     

Magnetic State and Magnetocaloric Effect of SmMnO3

We present a study of magnetization and magnetocaloric effect for the SmMnO₃ compound. This compound was synthesized by combustion reaction and its magnetic and structural properties studied by X-ray powder diffraction (XRD) and magnetization (M) measurements as a function of temperature and under magnetic fields. The XRD pattern at room temperature confirmed the presence of a single phase with orthorhombic structure. From magnetization versus temperature, we observe two magnetic orderings, the first one at 6 K due to Sm³⁺, and the other one at T _N =57(2) K is the anti-ferromagnetic long-range ordering. The magnetic entropy change, ΔS _M , was obtained from magnetization isotherms close to T _N where it reaches a maximum value of about 8.0 J/kg K for an applied field of 7 T.     

Magnetic and Transport Properties of Bilayered Perovskite Sr3Ir2O7

We report magnetic and transport properties of polycrystalline samples of bilayered perovskite Sr₃Ir₂O₇, which is synthesized by using high pressure technique. Magnetic susceptibility shows weak ferromagnetism below 290K with small size of remanent moment (10^–3B/Ir). Resistivity shows insulating behavior below 290K. We discuss the magnetism and conductivity in Sr₃Ir₂O₇ comparing with those of Sr₃Ru₂O₇, which has a quite similar crystal structure to Sr₃Ir₂O₇, from the view point of rotation angle of MO₆ (M=Ir, Ru) octahedra.     

A Review on the Regulation of Magnetic Transitions and the Related Magnetocaloric Properties in Ni-Mn-Co-Sn Alloys

In Ni-Mn-X(X=In,Sn,Sb) ferromagnetic shape memory alloys,a ferromagnetic transition from paramagnetic to ferromagnetic austenite and a martensitic transformation from ferromagnetic austenite to weak magnetic martensite occur in some particular composition ranges,in which abundant physical properties have been observed by the abrupt change of magnetization and resistivity around their transition temperatures in these alloys.Therefore,tuning the martensitic transformation temperature(TM) and enlarging the workingtemperature interval for Ni-Mn-X(X=In,Sn,Sb) alloys,are of great importance.In the present paper,we will focus on the effect of external factors,including pre-deformation,annealing,and high pressure annealing,on the magnetic transitions and the related magnetocaloric properties in Ni-Mn-Co-Sn ferromagnetic shape memory alloys.Our approaches and the main results in this particular field will be reviewed.     

Magnetic and Electrical Transport Properties of Er2O3-Doped La0.7Ca0.3MnO3 Composites

The (La_0.7Ca_0.3MnO₃)_1?x /(Er₂O₃) _x composites with x=0, 1, 2, 3, 4, 7, 9, 15, 17, and 20% were prepared by a solid state reaction process. The magnetic and electrical transport properties of the composites were investigated. The X-ray diffraction (XRD), scanning electronic microscopy (SEM), and the calculation of lattice parameters of La_0.7Ca_0.3MnO₃ (LCMO) indicated that there is no reaction between La_0.7Ca_0.3MnO₃ and Er₂O₃; especially, compared with pure LCMO, a new metal-insulator transition temperature (T _P2) was observed at a lower temperature in some composites with x=1,2,3,4, and 7%, which may result from the existence of a new phase related to Er₂O₃ dopant at grain boundaries or surfaces of LCMO grains. An enhancement of low field magnetoresistance (LFMR) is obtained at temperature below 130 K for the composites with higher Er₂O₃ content, but the intrinsic CMR at T _P1 decreased monotonously with increasing Er₂O₃ content. The increased LFMR results from the spin-dependent scattering and spin-polarized tunneling at the grain boundaries and the decreased intrinsic CMR due to the Double Exchange (DE) interaction between Mn³⁺ and Mn⁴⁺ ions.     

High Magnetic Field Dependence of Magnetodielectric Properties in Sr2CoSi2O7 Crystal

We have investigated magnetic and dielectric properties of åkermanite Sr₂CoSi₂O₇ single crystal in which the orbital hybridization is controllable by external magnetic fields. Sr₂CoSi₂O₇ shows the electric polarization that is originated from asymmetric orbital hybridization induced by magnetic field. This induced electric polarization was observed even at temperatures considerably higher than the magnetic transition temperature. The polarization data obtained for the paramagnetic phase are scaled with the square of the induced magnetization. By the discussion of the crystal symmetry, the space group of a polar state of åkermanite materials is probably Cmm2.     

Phase transformations in Er2Si2O7 ceramics

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

Er2O3掺杂Gd2(Zr0.8Ti0.2)2O7陶瓷的物理性能

用固相反应法制备(Gd_1-xEr_x)₂(Zr_0.8Ti_0.2)₂O₇(摩尔分数x=0,0.2,0.4)陶瓷并测试其晶体结构、显微形貌和物理性能,研究了Er₂O₃掺杂的影响。结果表明,(Gd_1-xEr_x)₂(Zr_0.8Ti_0.2)₂O₇陶瓷具有立方烧绿石结构,显微结构致密,在室温至1200℃高温相的稳定性良好;Er³⁺掺杂降低了陶瓷材料的热导率和平均热膨胀系数,当x=0.2时,其1000℃的热导率最低(为1.26 W·m^-1·k^-1)。同时,Er³⁺掺杂还提高了这种材料的硬度和断裂韧性。     

Magnetic Properties and Cryogenic Magneto-caloric Effect (MCE) in the Dy2FeCrO6 Oxide Compound

Journal of Superconductivity and Novel Magnetism - The magneto-caloric effects (MCEs) in various magnetic compounds and alloys are extensively studied due to their active applications in the field...     

Magnetic Properties of Ca3Ru2O7 Grown by a Floating Zone Method

We have succeeded in growing single crystals of Ca₃Ru₂O₇ by a floating zone method. The temperature dependence of magnetic susceptibility was measured in the temperature range from 2 to 300 K for the field along ab-plane and c-axis. The magnetic susceptibility shows anisotropic behavior. For T>55 K, the susceptibilities of both directions increase like the Curie–Weiss behavior with decreasing temperature. In the temperature range between 55 and 48 K, the susceptibility along ab-plane decreases steeply, while the one along c-axis is almost constant, which implies that the magnetic moment is aligned antiferromagnetically in the ab-plane. The susceptibilities drastically decrease in both directions at 48 K and are almost independent of temperature below 30 K.     

Synthesis,Structure and Magnetic Properties of Layered Perovskite Sm1.5SrBa0.5Mn2O7

The layered perovskite oxide Sm_1.5SrBa_0.5Mn₂O₇ was synthesized by the conventional method of co-precipitation. Its structure has been solved by powder X-ray diffraction. The diffraction patterns are consistent with the I4/mmm symmetry, with tetragonal lattice parameters a=3.8398(7) Å and c=20.3814(5) Å. The structure of Sm_1.5SrBa_0.5Mn₂O₇ is similar to Sr₃Ti₂O₇. Magnetic measurements were also performed in the temperature range 2–360 K. They showed a strong presence of antiferromagnetic interactions below Neel temperature T _N=25 K. The variation of the magnetization with the magnetic field in a temperature of 5 K was also analyzed. No saturation was observed up to the high applied magnetic field of 10 T.