Topological crystalline insulators represent a new state of matter, in which the electronic transport is governed by mirror-symmetry protected Dirac surface states. Due to the helical spin-polarization of these surface states, the proximity of topological crystalline matter to a nearby superconductor is predicted to induce unconventional superconductivity and, thus, to host Majorana physics. We report on the preparation and characterization of Nb-based superconducting quantum interference devices patterned on top of topological crystalline insulator SnTe thin films. The SnTe films show weak anti-localization, and the weak links of the superconducting quantum interference devices (SQUID) exhibit fully gapped proximity-induced superconductivity. Both properties give a coinciding coherence length of 120 nm. The SQUID oscillations induced by a magnetic field show 2π periodicity, possibly dominated by the bulk conductivity.

We investigate the influence of the barrier thickness of Co40Fe40B20 based magnetic tunnel junctions on the laser-induced tunnel magneto-Seebeck effect. Varying the barrier thickness from 1 nm to 3 nm, we find a distinct maximum in the tunnel magneto-Seebeck effect for 2.6 nm barrier thickness. This maximum is independently measured for two barrier materials, namely MgAl2O4 and MgO. Additionally, samples with an MgAl2O4 barrier exhibit a high thermovoltage of more than 350 µV in comparison to 90 µV for the MTJs with MgO barrier when heated with the maximum laser power of 150 mW. Our results allow for the fabrication of improved stacks when dealing with temperature differences across magnetic tunnel junctions for future applications in spin caloritronics, the emerging research field that combines spintronics and themoelectrics. arXiv:1706.08287v1 [cond-mat.mtrl-sci]

In this work, we study the influence of the magnetic proximity effect (MPE) in Pt on the total magnetic moment of thin film trilayer systems consisting of the ferromagnet (FM) Co adjacent to the heavy metals (HMs) Pt and Ta. We investigate the trilayer systems HM 1 /FM/HM 2 with different stacking order as well as a reference bilayer without any MPE. X-ray resonant magnetic reflectivity (XRMR) is a powerful tool to probe induced magnetism, especially when buried at interfaces in a multilayer. By using XRMR, we are able to obtain magnetic depth profiles of the structural, optical and magnetic parameters. By fitting the experimental data with a Gaussian-like magnetooptic profile taking the structural roughness at the interface into account, we can extract the magnetic moment of the spin-polarized layer. Comparing the obtained moments to the measured total moment of the sample, we can determine the impact of the MPE on the total magnetic moment of the system. Such information can be critical for analyzing spin transport experiments, including spin-orbit torque and spin Hall angle measurements, where the saturation magnetization M s has to be taken into account. Therefore, by combining magnetization measurements and XRMR methods we were able to get a complete picture of the magnetic moment distribution in these trilayer systems containing spin-polarized Pt.

A thermal gradient as the driving force for spin currents plays a key role in spin caloritronics. In this field the spin Seebeck effect (SSE) is of major interest and was investigated in terms of in-plane thermal gradients inducing perpendicular spin currents (transverse SSE) and out-of-plane thermal gradients generating parallel spin currents (longitudinal SSE). Up to now all spincaloric experiments employ a spatially fixed thermal gradient. Thus, anisotropic measurements with respect to well defined crystallographic directions were not possible. Here we introduce a new experiment that allows not only the in-plane rotation of the external magnetic field, but also the rotation of an in-plane thermal gradient controlled by optical temperature detection. As a consequence, the anisotropic magnetothermopower and the planar Nernst effect in a permalloy thin film can be measured simultaneously. Thus, the angular dependence of the magnetothermopower with respect to the magnetization direction reveals a phase shift, that allows the quantitative separation of the thermopower, the anisotropic magnetothermopower and the planar Nernst effect.Adding the spin degree of freedom to conventional charge-based electronics opens the field of spintronics 1,2 with promising advantages such as decreased electric power consumption and increased integration densities. While spinelectronics use only voltages as driving force for currents, thermal gradients and the interaction between spins and heat currents have already been shown to provide new effects. Spin caloritronics investigate these interactions and promotes the search for applications such as heat sensors or waste heat recyclers 3,4 , that can improve thermoelectric devices.One of the most important and well established phenomena in spin caloritronics is the longitudinal spin Seebeck effect (LSSE) [5][6][7][8][9][10][11] , which uses typically out-of-plane thermal gradients in magnetic thin films for the generation of a spin current parallel to the thermal gradient. This pure spin current is then injected into an adjacent non-magnetic conductor with high spin-orbit coupling, e.g. Pt, which transforms the spin current into an electric voltage via the inverse spin Hall effect (ISHE). In very recent investigations, the LSSE was even detected without any Pt and ISHE by the use of the anomalous Hall effect in Au 12 and by time-resolved magnetooptic Kerr effect in Au and Cu 13 . Besides the application of an out-of-plane thermal gradient, effects driven by in-plane thermal gradients were also investigated. The transverse spin Seebeck effect (TSSE), the spin current generation perpendicular to an in-plane thermal gradient, was reported for metals 14 , semiconductors 15 and insulators 16 . However, it has been noted that TSSE experiments in metals and semiconductors can be influenced by parasitic effects like the planar

X-ray resonant magnetic reflectivity (XRMR) is a powerful method to determine the optical, structural and magnetic depth profiles of a variety of thin film systems. Here, we investigate samples of different complexity all measured at the Pt L 3 absorption edge to determine the optimal procedure for the analysis of the experimental XRMR curves, especially for nontrivial bi- and multilayer samples that include differently bonded Pt from layer to layer. The software tool ReMagX is used to fit these data and model the magnetooptic depth profiles based on a highly adaptable layer stack which is modified to be a more precise and physically consistent representation of the real multilayer system. Various fitting algorithms, iterative optimization approaches and a detailed analysis of the asymmetry ratio features as well as χ 2 (goodness of fit) landscapes are utilized to improve the agreement between measurements and simulations. We present a step-by-step analysis procedure tailored to the Pt thin film systems to take advantage of the excellent magnetic sensitivity and depth resolution of XRMR.