Spin transfer torque driven higher-order propagating spin waves in nano-contact magnetic tunnel junctions

Abstract

Short wavelength exchange-dominated propagating spin waves will enable magnonic devices to operate at higher frequencies and higher data transmission rates. While giant magnetoresistance (GMR)-based magnetic nanocontacts are efficient injectors of propagating spin waves, the generated wavelengths are 2.6 times the nano-contact diameter, and the electrical signal strength remains too weak for applications. Here we demonstrate nano-contact-based spin wave generation in magnetic tunnel junctions and observe large-frequency steps consistent with the hitherto ignored possibility of second- and third-order propagating spin waves with wavelengths of 120 and 74 nm, i.e., much smaller than the 150-nm nanocontact. Mutual synchronization is also observed on all three propagating modes. These higher-order propagating spin waves will enable magnonic devices to operate at much higher frequencies and greatly increase their transmission rates and spin wave propagating lengths, both proportional to the much higher group velocity.

Quantum Spin-Wave Materials, Interface Effects and Functional Devices for Information Applications

“…In addition to their applications in memory, STT and SOT play an important role in spin-wave manipulation and the development of spin-wave devices (Madami et al, 2011;Divinskiy et al, 2018;Houshang et al, 2018;Fulara et al, 2019). Madami et al (2011) used STT effect to excite spin waves in a multilayer heterostructure as shown in Figure 6A (CoFe layer as reference/fixed layer and NiFe layer as free layer).…”

Interplay of Linear and Nonlinear Localization Mechanisms in Spin-Torque Oscillators with a Field Well

“…Naturally, the mode having the lowest threshold is excited firstly. At large currents, the generation can switch to another regime, e.g., the excitation of higher-order propagating modes [30], second bullet mode [31], multibullet mode [23], mode hopping [32], etc. Here, we are not interested in this high-drivingcurrent dynamics and consider only the lowest excited mode.…”

Intensity enhancement of ferromagnetic resonance modes in exchange coupled magnetic multilayers

“…Using magnetic materials as building blocks for these devices allows to reduce their size, taking advantage of their natural resonance in the order of GHz [13,14], which is typically exploited in areas such as magnonics [15][16][17] and spintronics [18][19][20]. In the case of high frequency devices, the use of magnetic materials makes it possible to fabricate micrometer and nanometer devices such as circulators [21,22], phase shifters [23,24], filters [25,26], and frequency sources [27][28][29][30][31][32]. Another characteristic that makes magnetic thin films attractive for high frequency applications is the possibility to control their magnetic properties with electrical signals, providing a path for adjusting dynamically the behavior of magnetic high frequency devices.…”