Research Projects

In the beginning of this century, the journey of spintronics have started with the development of the magnetoresistive sensors, GMR and TMR. Now they are widely used as magnetic read heads in memory devices of all commercial computers. The field of spintronics has taken the next step with conceptualization of non-volatile random access memory (RAM): Magnetoresistive RAM (MRAM), spin-transfer torque RAM (STT-RAM). All these devices are MTJs of magnetically ordered materials which process or store the data using quantum mechanical properties of spin angular momentum of electrons. These RAMs can store data for a longer period of time as well as data reading and writing operations can be executed in these devices extremely fast with a very small spin-current/ magnetic field due to extremely fast dynamics of spins of the magnetic layers. All these quantum devices are based on electron’s spin and they have demonstrated much enhanced performance compared to charged based electronic devices. Though one of the main challenges with STT-RAM is the requirement of comparatively large current. A new effect, named Spin-orbit torque (SOT) effect is realized in the bilayer Ferromagnetic (FM) - Heavy metal (HM) heterostructure where switching of magnetic moment of the FM layers is achieved by the torque produced by a spin polarized current injected from the HM where such a current is produced due to spin hall effect (SHE) mediated by strong spin-orbit coupling (SOC) of the HM. For a practical SOT device, a ferromagnetic material with perpendicular magnetic anisotropy (PMA) and magnetic ordering temperature (Tc) well above room temperature is required. So far, mostly FM alloy-Pt heterostructure is used to achieve SOT-RAM which has complicated design procedure. There is new class of materials like Graphite where 2D layers of atoms create a bulk material by weak Van der Waals (vdW) bond between them. These materials can be cleaved down to monolayer just by mechanical exfoliation. They are called vdW materials. They show large variety of electronic and magnetic ground state which often prevails down to monolayer. In this project, we shall design vdW FM materials with PMA and Tc greater than 400 K in single crystalline form, characterize the materials down to few nm thickness limit. In recent times, the heavy metal used in the SOT device is Platinum which is definitely not economical. We shall explore different vdW heavy metals and semimetals with large SOC to generate spin current. SOT bilayer devices will be made with few layers of vdW FMs and Metals. The magnetic switching will be studied by anomalous Hall voltage measurement with in-plane field. The SOT switching efficiency will be measured by second harmonic Hall measurement. At the end of this project, we expect to design an efficient SOT magnetic switching device.

Spin-Orbit Torque, Ferromagnet, Van der Waals(VdW) materials, 2D Spintronics, Anomalous Hall Effect, Second Harmonic Hall