Magnetic Resonance Study of Polycrystalline MnAu2 at 100 GHz

Abstract

We report the results of magnetic resonance studies at high microwave frequencies in metallic, metamagnetic, poly crystalline MnAu2. The investigation covered microwave frequencies from 95 to 119 GHz, temperatures from 4.20 to 400 o K, and magnetic field intensities up to 50 kOe. No resonance was observed in the spiral magnetic phase at our frequencies. At fields above that necessary to induce a ferromagnetic component in the spiral-spin system, a temperatureand frequency-dependent peak was observed in the microwave power absorption, as a function of magnetic field applied in the plane of the disk-shaped sample. We have interpreted this absorption as ferromagnetic resonance in a system with large uni-axial magnetic anisotropy. Values of the Lande g-factor and uni-axial anisotropy constant at low temperatures are determined from the data, but with large experimental uncertainty due to severe magnetic hysteresis exhibited with field cycling.

Growth and characterization of MnAu2 films

“…This is in good agreement with the bulk values of a= 0.336 nm and c= 0.876 nm. [9] The density of the films was analyzed using x-ray reflectivity to be 14.95 g/cm 3 and also agrees well with the previously determined x-ray density of 15.00 g/cm 3 . [9] The Mn-Au film grown on Si/Si 3 N 4 substrate using the same deposition conditions showed similar x-ray results as that of on fused silica.…”

Collapse and control of theMnAu2spin-spiral state through pressure and doping

“…The experimental lattice parameters are a = 3.370 Å and c/a = 2.599, yielding a volume of 49.741 Å 3 /formula unit, and the Wyckoff positions for Mn and Au are 2a and 4e, respectively, with the internal experimental height for Au z Au = 0.34 (fractional coordinates) [30,31]. To simulate pressure, we began with the MnAu 2 unit cell from experiment with tetragonal symmetry and varied the lattice parameters a and c to set the volume [32].…”

Role of Adrenergic Mechanisms in Development and Therapy of Open-Angled Glaucoma

“…Adrenergic innervation of vessels in this area have been described (Ehinger 1966) and it is this system which appears to provide the means of modifying bloodflow both to the ciliary processes and to the intraand epi-scleral plexuses. The general nature of this neurovascular concept of regulation of intraocular pressure and aqueous humour dynamics has recently found strong support in the exciting and extensive theoretical analysis of Hart (1970).…”