These two authors contributed equally to this work. The ability to manipulate antiferromagnetic (AF) moments is a key requirement for the emerging field of antiferromagnetic spintronics. Electrical switching of bi-state AF moments has been demonstrated in metallic AFs, CuMnAs and Mn 2 Au. 1-5 Recently, current-induced "saw-tooth" shaped Hall resistance was reported in Pt/NiO bilayers, 6-9 while its mechanism is under debate. Here, we report the first demonstration of convincing, non-decaying, steplike electrical switching of tri-state Néel order in Pt/-Fe 2 O 3 bilayers. Our experimental data, together with Monte-Carlo simulations, reveal the clear mechanism of the switching behavior of -Fe 2 O 3 Néel order among three stable states. We also show that the observed "saw-tooth" Hall resistance is due to an artifact of Pt, not AF switching, while the signature of AF switching is step-like Hall signals. This demonstration of electrical control of magnetic moments in AF insulator (AFI) films will greatly expand the scope of AF spintronics by leveraging the large family of AFIs.Spin-orbit torque (SOT) induced switching of ferromagnets (FM) by an adjacent heavy metal (HM) has raised wide interests in recently years, 10-12 where a charge current in the HM generates spins at the HM/FM interface via the spin Hall effect (SHE). AFs offer the advantage of no stray field, robustness against external field, THz response, and abundance of material

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Bloch surface waves (BSWs) on one-dimensional photonic crystals (1DPC) have been used to beam the fluorescence emission from the dye molecules. All dielectric 1DPC displays its low propagating loss, narrow resonance and the absence of absorption or quenching. In this letter, back focal plane imaging reveals that in addition to the BSW mode, a guided mode and cavity mode also exist in the 1DPC which all couple with the excited dye molecules. The appearance of these modes is sensitive to the wavelength of the fluorescence and alters the beaming effect by the 1DPC. Numerical simulations verify the existence of these modes which are consistent with the experimental results. Comparisons between the Bloch surface wave-coupled emission (BWCE) and surface plasmon-coupled emission (SPCE) are also presented for a more clear understanding of the multilayered film-enabled directional emission.

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To date, magnetic proximity effect (MPE) has only been conclusively observed in ferromagnet (FM) based systems. We report the observation of anomalous Hall effect and anisotropic magnetoresistance in angular dependent magnetoresistance (ADMR) measurements in Pt on antiferromagnetic (AF) α-Fe2O3(0001) epitaxial films at 10 K, which provide evidence for the MPE. The Néel order of α-Fe2O3 and the induced magnetization in Pt show a unique ADMR compared with all other FM and AF systems. A macrospin response model is established and can explain the AF spin configuration and all main ADMR features in the Pt/α-Fe2O3 bilayers.

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We measure the spin Hall angle in Au layers of 5 to 100 nm thicknesses by spin pumping from Y 3 Fe 5 O 12 epitaxial films grown by ultrahigh vacuum, off-axis sputtering. We observe a striking increase in the spin Hall angle for Au layers thinner than the measured spin diffusion length of 12.6 nm. In particular, the 5 nm Au layer shows a large spin Hall angle of 0.087, compared to those of 0.016 and 0.017 for the 50 and 100 nm Au layers, respectively, suggesting that the top surface plays a dominant role in spin Hall physics when the spin current is able to reach it. Other spin pumping related parameters, including Gilbert damping enhancement, interfacial spin mixing conductance, and spin current are also determined for Au layers of various thicknesses.Given the pervasive role ultrathin films in electrical and spin transport applications, this result emphasizes the importance of considering the impact of the top surface and reveals the possibility of tuning critical spin parameters by film thickness. PACS: 72.25.Ba, 76.50.+g, 72.25.Mk, 75.70.Ak 2The spin Hall effect (SHE) and its reciprocal process, the inverse spin Hall effect (ISHE), have generated intense interest in recent years as a means of producing, manipulating, and detecting spin currents in nonmagnetic materials, opening new routes to spin-based electronic applications.1-13 The ability to convert an unpolarized electrical current into a spin current can be quantitatively described by the spin Hall angle (θ SH ).14,15 θ SH is a material-specific quantity that arises from spin-orbit coupling (SOC). Its magnitude and sign are primarily determined by atomic number, and for transition metals, by the d-orbital filling. [16][17][18][19] Au is a transition metal with a large atomic number of 79, which should lead to strong SOC and hence a large θ SH . As a result, both SHE and ISHE in Au have been extensively studied by various techniques. 20-28These studies have reported values of θ SH for Au between 0.25% (0.0025) and 11% (0.11 during film growth and the substrate rotates at 10 degrees/sec to achieve optimal film uniformity.A radio-frequency power of 60 W is used for YIG sputtering, which gives a deposition rate of 0.51 nm/min. The Au is grown in-situ on the YIG film at room temperature by off-axis DC sputtering at a deposition rate of 2.24 nm/min. The crystalline quality of the YIG films and YIG/Au bilayers are examined by X-ray diffraction (XRD) and X-ray reflectivity (XRR) using a 3 Bruker D8 Discover high-resolution triple-axis X-ray diffractometer, and scanning transmission electron microscopy (STEM) using an FEI probe-corrected Titan 3 80-300 S/TEM. where e is the electron charge, σ Au is the Au conductivity, λ SD is the spin diffusion length in Au, is the effective interfacial spin mixing conductance, L is the sample length, P = 1.21 is a factor due to the ellipticity of magnetization precession, 5 γ is the gyromagnetic ratio, h rf = 0.25Oe is the rf magnetic field in the EPR cavity at P rf = 200 mW, and α is the Gilbert damping constant of ...

The saturation magnetization of Y3Fe5O12 (YIG) epitaxial films 4 to 250 nm in thickness has been determined by complementary measurements including the angular and frequency dependencies of the ferromagnetic resonance fields as well as magnetometry measurements. The YIG films exhibit state-of-the-art crystalline quality, proper stoichiometry, and pure Fe3+ valence state. The values of YIG magnetization obtained from all the techniques significantly exceed previously reported values for single crystal YIG and the theoretical maximum. This enhancement of magnetization, not attributable to off-stoichiometry or other defects in YIG, opens opportunities for tuning magnetic properties in epitaxial films of magnetic insulators.