N°19 - 23 September 2016 - SPIN TORQUE RESONANT EXPULSION OF THE VORTEX CORE FOR AN EFFICIENT RADIO-FREQUENCY DETECTION SCHEME

A. S. Jenkins1, R.Lebrun1, E. Grimaldi1, S.Tsunegi1,2, P. Bortolotti1, H. Kubota2, K.Yakushiji2, A. Fukushima2, G.deLoubens3, O.Klein3, S.Yuasa2 and V. Cros1
 
1 Unité Mixte de Physique CNRS, Thales and Université Paris Sud, 91767 Palaiseau, France
2 Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Tsukuba, Japan
3 Service de Physique de l’Etat Condensé (CNRS URA 2464), CEA Saclay, 91191 Gif-sur-Yvette, France
 
Spin-polarised radio-frequency currents, whose frequency is equal to that of the gyrotropic mode, will cause an excitation of the core of a magnetic vortex confined in a magnetic tunnel junction. When the excitation radius of the vortex core is greater than that of the junction radius, vortex core expulsion is observed, leading to a large change in resistance, as the layer enters a predominantly uniform magnetisation state. Unlike the conventional spin-torque diode effect, this highly tunable resonant effect will generate a voltage which does not decrease as a function of rf power, and has the potential to form the basis of a new generation of tunable nanoscale radio-frequency detectors. 
 
Nature Nanotech 11, 360-364 (2016)
doi:10.1038/nnano.2015.295
 
 
Figure 1: Radio frequency current dependence. a,b, The rectified voltage for observed for the core expulsion (a) and the spin-torque diode measurements (b) taken at 6 and 0 mA, respectively, for IRF = 0.2 mA. c, The generated voltage, ΔV as a function of IRF for a range of d.c. currents at Hperp = 150 mT and θH = 90.1°. The core expulsion shows a constant ΔV as a function of IRF, whereas the resonant excitation decreases linearly with IRF.