Magnetic resonance in Ge0.99Mn0.01 nanowires

Effect of magnetic defects and dimensionality on the spin dynamics of GeMn systems: Electron spin resonance measurements

“…Static and dynamic magnetic properties of these structures have been investigated in detail and published elsewhere. 12,15,[19][20][21] The magnetic-resonance spectra have been measured as field dependences of the microwave absorption, dP / dB, in Varian-300 spectrometer at rfs of 9.45 and 24.17 GHz and a modulation frequency of 100 kHz at T = 5 -300 K. Different orientations of the rf magnetic field with a respect to the film plane and the NW long axis have been investigated. The static magnetic field was always kept perpendicular to the rf one.…”

“…Despite temperature related transformations of lines 1-3, the overall shape of the spectrum remains the same up to T = 300 K. In our previous works we performed a detailed analysis of ESR spectra in DMS NWs and verified that all four lines corresponded to magnetic resonances in different magnetic subsystems. [19][20][21] In particular, we have demonstrated that lines 1 and 2 have the same temperature dependencies and, therefore, may correspond to resonances in the same kind of magnetic defects. It was also shown that the ratio of the integral intensities of lines 1 and 3 and line 2 is similar to the ratio of Mn ions with the oxidation state +3 to those with the state +2.…”

“…Alternatively, in NWs only orientation dependencies of main resonant lines are comparable, whereas their temperature dependencies differ. [19][20][21] The thin-film spectrum shown in Fig. 2 has been measured in a perpendicular geometry, i.e., B dc was applied normal to the film plane.…”

“…Perfect dilution of Mn ions in the host accompanied by a high Curie temperature, correlation between electrical and magnetic properties, existence of charge and spin carriers in a magnetically ordered lattice, [19][20][21] and other remarkable features of these systems make them attractive for spintronic applications. Although Ge 1−x Mn x nanowires ͑NWs͒ have a relatively simple and magnetically homogeneous structure consisting of localized ions ͑Mn 3+ and Mn 2+ ͒ and spin-polarized holes, the nature of their ferromagnetism is yet to be understood.…”

Electron spin resonance in Ge nanowires doped with Mn

“…Earlier we have shown that the ESR spectrum in Ge 0.99 Mn 0.01 NWs comprises three components corresponding to subsystems of Mn ions (lines 1-3) and the fourth one related to the resonance on spin-polarized charge carriers (line 4) [3]. Increasing the Mn concentration does not change the overall shape and position of the ESR spectrum on charge carriers, but leads to a smaller number of FMR lines, loss of their anisotropy and widening of lines related to Mn ions.…”