Negative Differential Resistance Induced by Mn Substitution at SrRuO3/Nb:SrTiO3 Schottky Interfaces

High-quality all-oxide Schottky junctions fabricated on heavily Nb-doped SrTiO3 substrates

We present a detailed investigation of the electrical properties of epitaxial La0.7Sr0.3MnO3/SrTi0.98Nb0.02O3 Schottky junctions. A fabrication process that allows reduction of the junction dimensions to current electronic device size has been employed. A heavily doped semiconductor has been used as a substrate in order to suppress its series resistance. We show that, unlike standard semiconductors, high-quality oxide-based Schottky junctions maintain a highly rectifying behavior for doping concentration of the semiconductor larger than 10^20 cm^(-3). Moreover, the junctions show hysteretic cu…

Al-Substitution Effects on Physical Properties of the Colossal Magnetoresistance Compouns La0.67ca0.33mno3

We present a detailed study of the polycrystalline perovskite manganites La0.67Ca0.33AlxMn1-xO3 (x = 0, 0.1, 0.15, 0.5) at low temperatures and high magnetic fields, including electrical resistance, magnetization, ac susceptibility. The static magnetic susceptibility was also measured up to 1000 K. All the samples show colossal magnetoresistance behavior and the Curie temperatures decrease with Al doping. The data suggest the presence of correlated magnetic clusters near by the ferromagnetic transition. This appears to be a consequence of the structural and magnetic disorder created by the ran…

Hysteretic current-voltage characteristics and resistance switching at a rectifying Ti/Pr$_{0.7}$Ca$_{0.3}$MnO$_{3}$ interface

We have characterized the vertical transport properties of epitaxial layered structures composed of Pr$_{0.7}$Ca$_{0.3}$MnO$_{3}$ (PCMO) sandwiched between SrRuO$_{3}$ (SRO) bottom electrode and several kinds of top electrodes such as SRO, Pt, Au, Ag, and Ti. Among the layered structures, Ti/PCMO/SRO is distinct due to a rectifying current-voltage ($I$--$V$) characteristic with a large hysteresis. Corresponding to the hysteresis of the $I$--$V$ characteristics, the contact resistance of the Ti/PCMO interface reversibly switches between two stable states by applying pulsed voltage stress. We pr…

Magnetic and electrical resistance behaviour of the oxides, Ca$_{3-x}$Y$_x$LiRuO$_6$ (x= 0.0, 0.5 and 1.0)

We have investigated the magnetic and electrical resistance behaviour of Ca$_{3-x}$Y$_x$LiRuO$_6$. The parent compound exhibits magnetic ordering from Ru sublattice at a rather high temperature, 113 K. Though the paramagnetic Curie temperature ($θ$$_p$) is negative indicative of antiferromagnetic ordering, the large magnitude (-250 K) of $θ$$_p$ reveals complex nature of the magnetism in this compound. Ru ions appear to be in the pentavalent state. We note that the Néel temperature undergoes only a marginal reduction by Y substitution. All these compositions are found to be insulators and thus…

Y替代TmVO4中无序诱导的局域应变分布

Disorder-induced local strain distribution in Y-substituted TmVO4

本文通过低温热容测量研究Y替代TmVO4中化学替代诱导的局域应变分布，发现局域应变并非随机不相关，而是存在显著格点间关联，并讨论了其对随机有效场理论模型适用范围的启示。

Tuning the Room Temperature Ferromagnetism in Fe5GeTe2 by Arsenic Substitution

In order to tune the magnetic properties of the cleavable high-Curie temperature ferromagnet Fe$_{5-x}$GeTe$_2$, the effect of increasing the electron count through arsenic substitution has been investigated. Small additions of arsenic (2.5 and 5%) seemingly enhance ferromagnetic order in polycrystalline samples by quenching fluctuations on one of the three magnetic sublattices, whereas larger As concentrations decrease the ferromagnetic Curie temperature ($T_{\rm C}$) and saturation magnetization. This work also describes the growth and characterization of Fe$_{4.8}$AsTe$_2$ single crystals t…