Thermal and Magnetocaloric Properties of La0.7Sr0.3 – xBaxMnO3 Manganites

Physics of the Solid State - The results of studying the effect produced by the partial substitution of Sr2+ ions by Ba2+ ions on the thermophysical and magnetocaloric properties of...     

Effect of Isovalent Cation Substitution on the Thermal,Caloric, and Magnetocaloric Properties of the (La1 – yEuy)0.7Pb0.3MnO3 Manganites

Physics of the Solid State - Crystalline samples of the (La1 – yEuy)0.7Pb0.3MnO3 (y = 0, 0.2, 0.4, 0.5, 0.6, and 0.8) manganite solid solutions have been grown. Temperature...     

(La0.7Sr0.3MnO3)m(BiFeO3)n超晶格间隔的La0.7Sr0.3MnO3三明治结构制备及表征

采用射频磁控溅射的方法在SrTiO3(001,基片上制备了(La0.7Sr0.3MnO3)m(BiFeO3)n超晶格间隔的La0.7Sr0.3MnO3三明治结构.X射线衍射分析证明(La0.7Sr0.3MnO3)m(BiFeO3)n具有明显的超晶格结构.电流垂直于薄膜表面测得的电阻-温度关系表明.La0.7Sr0.3MnO3)m(BiFeO3)n超晶格薄膜在290 K有金属-绝缘体转变,略低于单层La0.7Sr0.3MnO3薄膜的转变温度.电流在0.01-10 mA范围内,观察到薄膜的峰值电阻随电流增大而减小,峰值变化率远大于单层La0.7Sr0.3MnO3薄膜,且随着超晶格周期厚度的增加而增大.低温下,电流-电压曲线表明其导电机制应主要为空间载子限制,且显示较大的电压偏置,表现出肖特基结的特性.     

La0.7-xGdxSr0.3MnO3体系中的相分离

采用固相反应法制备了样品La0.7-xGdxSr0.3MnO3(x=0.00,0.20,0.30,0.40,0.50).通过测量样品的M～T曲线,ESR曲线,研究了La0.7-xGdxSrO0.3MnO3,体系中的相分离现象及相分离与CMR之间关系.结果表明:当x=0.30,0.40时,在PM-FM相变区产生相分离,并且磁电阻MR得到增强.研究结果表明:La0.7-xGdx Sr0.3MnO3中的相分离与Gd在A位的占位情况紧密相关,磁电阻MR的增强是在外磁场作用下,铁磁区扩大顺磁区减小引起的.     

La0.7-xDyxSr0.3MnO3(0.00≤x≤0.30)体系低温磁行为和电阻率的反常

通过测量样品的磁化强度-温度曲线、电阻率-温度曲线及磁电阻-温度曲线.研究了 Dy 掺杂(0.00≤x≤0.30)对 La_(0.7-x)Dy_xSr_(0.3)MnO_3 体系磁电性质的影响.实验发现,随 Dy 掺杂量的增加,体系磁结构从长程铁磁有序向自旋团簇玻璃态、反铁磁状态转变；x=0.20、0.30时的低温磁行为发生异常,电行为存在低温电阻率极小值现象.这些奇特现象不仅来源于掺杂引起的晶格效应,也来源于掺杂引起的额外磁性耦合.     

Correlation between the Fluorine Ion Conductivities of Sr1 – xRxF2 + x (CaF2 Type) and R1 – ySryF3 – y (LaF3 Type) Crystals in the SrF2–RF3 Systems (R = La–Nd)

Physics of the Solid State - The “conductivity logarithm–composition” correlation logσdc(x) = ax + b has been revealed for the strongly nonstoichiometric fluorite...     

Optical Properties of (ZrO2)1 – x(Y2O3)х (х = 0–0.037) Crystals Grown by Directional Crystallization of the Melt

Optics and Spectroscopy - The luminescent and optical properties of materials based on zirconium(IV) oxide grown by crystallization of ZrO2 melts with 0, 2.0, 2.5, 2.8, and 3.7 mol % of Y2O3 are...     

La0.7-xDyxSr0.3MnO3中的相分离和输运行为

通过测量样品的M-T曲线、 M-H曲线、 ESR曲线、ρ-T曲线和MR-T曲线, 研究了Dy掺杂(0.0≤x≤0.30)对La0.7Sr0.3MnO3磁电性质的影响. 实验结果表明 在TC处所有样品都经历了顺磁到铁磁的转变; 当T＜TC时, 掺杂样品进入自旋团簇玻璃态, 低温时显示出反铁磁性; x=0.20时, 样品在TC以上温区发生相分离; Dy掺杂引起的磁结构变化将导致CMR效应.     

Ultrafast optical probes of dynamic behavior in La0.7Sr0.3MnO3/YBa2Cu3O7 − δ/La0.7Sr0.3MnO3 heterostructure

Ultrafast pump-optical probe spectroscopy was used to analyze carriers dynamics behavior in La_0.7Sr_0.3MnO₃/YBa₂Cu₃O_{7 ? δ}/La_0.7Sr_0.3MnO₃ heterostructure. Our results show the pump signal ΔR/R for higher laser power (such as 21 and 41 mW), below T _c , first goes positive, then crosses zero and goes negative, before relaxing back to equilibrium over a time scale of a few ten picoseconds. We extract the characteristic relaxation time of the different process by fitting the data at these powers with a three-exponential decay. For higher laser power, the long characteristic relaxation time are obtained, which implies the competition between FM order and SC order in the La_0.7Sr_0.3MnO₃/YBa₂Cu₃O_{7 ? δ}/La_0.7Sr_0.3MnO₃ heterostructure.     

Haven Correlation Parameter for Diffusion of Fluorine in Superionic Conductors La1 – ySryF3 – y

Physics of the Solid State - The processes of electric charge transfer (conductivity) and mass transfer (diffusion) in La1 ‒ ySryF3 – y superionic...     

Effect of the Chemical Composition of TlIn1 – xErxS2 (0 ≤ x ≤ 0.01) Crystals on Their Dielectric Characteristics and the Parameters of Localized States

Physics of the Solid State - The frequency dependences of the real (ε') and imaginary (ε'') parts of the complex dielectric permittivity, the dielectric loss tangent...     

Synthesis and Gas-Sensing Properties of MnO2 – x and MnO2 – x/CuO-Coated Multiwalled Carbon Nanotube Nanocomposites

Physics of the Solid State - Nanocomposites based on multiwall carbon nanotubes (MWCNTs) impregnated with manganese oxide MnO2 – x and copper oxide CuO are synthesized and...     

Ultrafast Photoelectric Effects in Heterojunctions of La0.7Sr0.3MnO3 and Si

Ultrafast photoelectric effects have been observed in p-n heterojunctions of La0.7Sr0.3MnO3(LSMO)/Si and LSMO/SrTiO3_/Si for the first time. The rise time was about 1 ns and the full width at half maximum was about 2ns for the photovoltaic pulse when the heterojunction was irradiated by a laser of -25 ps pulse duration and 1064 nm wavelength. The photovoltaic sensitivity was as large as 435 mV//mJ for a 1064 nm laser pulse. No such pulse was observed with irradiation from a pulsed 10.6 μm CO2 laser.     

La0.7Ca0.3Mn1-xCrxO3 (0.01≤x≤0.60)的低温热导

测量了锰位掺Cr系列巨磁阻多晶样品La0 .7Ca0 .3Mn1-xCrxO3(0 .0 1≤x≤ 0 .6 0 )的热导 ,实验温区 77～ 30 0K .随着Cr掺杂浓度x的增加 ,热导率κ(T)在所测温区内受到的压制变大 ,但当x =0 .6 0时 ,热导值却有较大的回升 ,显示了Cr掺入对晶格结构局部涨落的影响 .随温度降低 ,低掺杂样品在MI(金属 绝缘体 )转变点附近热导率κ(T)由dκ/dT >0变成dκ/dT<0 ,而高掺杂样品无MI转变 ,热导率随温度降低而减小 ,即dκ/dT >0 ,我们认为这是由载流子处于局域或巡游状态时与晶格的相互作用不同而导致的 .     

Elastic Constants and Related Mechanical Properties of YxIn1 – xN Ternary System

Physics of the Solid State - Using a pseudo-potential approach within the virtual crystal approximation, the elastic properties of YxIn1&nbsp;–&nbsp;xN semiconductor ternary alloys in...     

Martensitic Transformation,Magnetotransport Properties,and Magnetocaloric Effect in Ni47 – xMn42 + xIn11 Alloys (0 ≤ x ≤ 2)

Physics of the Solid State - The structure, electrical and magnetic properties of Ni47&nbsp;–&nbsp;xMn42&nbsp;+&nbsp;xIn11 (0 ≤ x ≤ 2) alloys upon changing the...     

Features of magnetic properties of La x MnO3 + δ (0.815 ≤ x ≤ 1.0)

Magnetic and resonance studies of the system of polycrystalline samples of self-doped manganites La _x MnO_{3 + δ} (x = 0.815, 0.90, 0.94, 0.97, and 1.0) have been performed in a temperature range of 77–300 K. According to ⁵⁵Mn NMR data, all samples contain a ferromagnetic phase at 77 K. As the defect density increases (x changes from 1.0 to 0.815), samples become more magnetically ordered. In this case, the ferromagnetic state of the system gradually changes from a mixed state in which both ferromagnetic insulating (basic) and ferromagnetic metal (for x = 0.97 and 1.0) phases coexist to only the ferromagnetic metal state (for x = 0.815 and 0.90). It has been shown that both ferromagnetic metal and ferromagnetic insulating phases are inhomogeneous, and either phase consists of two phases with different dynamics of nuclear spins and different Curie temperatures. The diagram of the magnetic phase state of the La _x MnO_{3 + δ} system (x = 0.815, 0.90, 0.94, 0.97, 1.0) has been constructed for a temperature range of 120–240 K and Mn⁴⁺ contents of 12–30%.     

Synthesis,Structure, and Thermophysical Properties of Pb10 – xBix(GeO4)2 + xVO4)4 – x (x = 0–3) in the Temperature Range of 350–950 K

Physics of the Solid State - The Pb10&nbsp;–&nbsp;xBix(GeO4)2&nbsp;+&nbsp;x(VO4)4&nbsp;–&nbsp;x (x = 0–3) compounds with an apatite structure have been...     

Current Relaxation in TlGa1 – xDyxSe2 (x = 0.01, 0.03) Single Crystals

Physics of the Solid State - The low-temperature relaxation processes in TlGa1&nbsp;–&nbsp;xDyxSe2 (x = 0.01, 0.03) single crystals have been studied experimentally. The physical...