Publications by authors named "Need R"

The effect of oxygen reduction on the magnetic properties of LaFeO (LFO) thin films was studied to better understand the viability of LFO as a candidate for magnetoionic memory. Differences in the amount of oxygen lost by LFO and its magnetic behavior were observed in nominally identical LFO films grown on substrates prepared using different common methods. In an LFO film grown on SrTiO (STO) substrate, the original perovskite film structure was preserved following reduction, and remnant magnetization was only seen at low temperatures.

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Non-collinear antiferromagnets (AFMs) are an exciting new platform for studying intrinsic spin Hall effects (SHEs), phenomena that arise from the materials' band structure, Berry phase curvature, and linear response to an external electric field. In contrast to conventional SHE materials, symmetry analysis of non-collinear antiferromagnets does not forbid non-zero longitudinal and out-of-plane spin currents with polarization and predicts an anisotropy with current orientation to the magnetic lattice. Here, multi-component out-of-plane spin Hall conductivities are reported in L1 -ordered antiferromagnetic PtMn thin films that are uniquely generated in the non-collinear state.

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We report on the evolution of the average and depth-dependent magnetic order in thin-film samples of biaxially stressed and electron-doped EuTiO for samples across a doping range < 0.1 to 7.8 × 10 cm.

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Low-dimensional quantum materials that remain strongly ferromagnetic down to monolayer thickness are highly desired for spintronic applications. Although oxide materials are important candidates for the next generation of spintronics, ferromagnetism decays severely when the thickness is scaled to the nanometer regime, leading to deterioration of device performance. Here, a methodology is reported for maintaining strong ferromagnetism in insulating LaCoO (LCO) layers down to the thickness of a single unit cell.

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Article Synopsis
  • Topology and strong electron correlations are key elements in new quantum materials, but their study together in experiments is still limited.
  • Strongly correlated Weyl semimetals with magnetism, like antiferromagnetic MnSn, provide a unique opportunity to investigate new phenomena in topological materials and spintronics.
  • The research highlights the successful synthesis of epitaxial MnSn films with a broader composition range, showing that as magnetic Mn replaces Sn, strong correlations lead to effects like the Kondo effect and significant changes in electronic properties, which are demonstrated by notable DC Hall effects and enhanced terahertz Faraday rotation.
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Charge transfer in oxide heterostructures can be tuned to promote emergent interfacial states, and accordingly, has been the subject of intense study in recent years. However, accessing the physics at these interfaces, which are often buried deep below the sample surface, remains difficult. Addressing this challenge requires techniques capable of measuring the local electronic structure with high-resolution depth dependence.

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Bismuth selenide (BiSe) is a prototypical 3D topological insulator whose Dirac surface states have been extensively studied theoretically and experimentally. Surprisingly little, however, is known about the energetics and dynamics of electrons and holes within the bulk band structure of the semiconductor. We use mid-infrared femtosecond transient reflectance measurements on a single nanoflake to study the ultrafast thermalization and recombination dynamics of photoexcited electrons and holes within the extended bulk band structure over a wide energy range (0.

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Here we present polarized neutron reflectometry measurements exploring thin film heterostructures composed of a strongly correlated Mott state, GdTiO_{3}, embedded with SrTiO_{3} quantum wells. Our results reveal that the net ferromagnetism inherent to the Mott GdTiO_{3} matrix propagates into the nominally nonmagnetic SrTiO_{3} quantum wells and tracks the magnetic order parameter of the host Mott insulating matrix. Beyond a well thickness of 5 SrO layers, the magnetic moment within the wells is dramatically suppressed, suggesting that quenched well magnetism comprises the likely origin of quantum critical magnetotransport in this thin film architecture.

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