arXiv subjects

Tianli Jin

Publications and source records attributed to Tianli Jin.

6 recordsLinked to original sources

arXiv2026

Current-Driven Magnetization Switching via Zhang-Li Torque

Current-driven magnetization switching is currently governed by two established mechanisms: the Slonczewski spin-transfer torque (STT) and the spin-orbit torque (SOT). Here we identify the Zhang-Li STT as a third mechanism that operates on a different physical footing. Using micromagnetic simulations, we show that the interfacial Dzyaloshinskii-Moriya interaction (iDMI) inevitably creates spatial magnetization gradients at device edges, enabling the Zhang-Li torque to drive deterministic, field-assisted switching that fully reproduces all hallmark behaviors of SOT, including polarity control and effective-field characteristics. Our work establishes the Zhang-Li torque as an autonomous switching pathway, redefining the physical picture of current-induced magnetization reversal and providing new design principles for spintronic devices.

cond-mat.mes-hall↗

arXiv2026

Magnetic Orbital Hall Effect in Altermagnet RuO$_2$

Orbital angular momentum provides an alternative channel for current-induced magnetization switching beyond conventional spin--orbit coupling. While orbital Hall effects have been observed in several nonmagnetic materials, their manifestation in symmetry-compensated magnetic systems remains unexplored. Here, we report experimental evidence for a magnetic orbital Hall effect in RuO$_2$. In RuO$_2$(101)/Pt/Co heterostructures, we observe a pronounced unconventional torque characterized by a large out-of-plane component, strong crystalline anisotropy, and deterministic field-free switching of a perpendicular ferromagnet over a wide range of RuO$_2$ thicknesses. The torque exhibits a non-monotonic dependence on Pt thickness, reaching a maximum at 1.5~nm, and displays a long-range RuO$_2$ thickness ($t_{\mathrm{RuO}_2}$) dependence that saturates for $t_{\mathrm{RuO}_2}>100~\mathrm{nm}$. These features cannot be reconciled with conventional spin-current mechanisms. Rather, they indicate a magnetic orbital Hall effect in RuO$_2$ that could originate from exchange-induced momentum-dependent band splitting and its interplay with spin--orbit and crystal-field coupling, with the generated orbital current converted into torque in Pt. Our findings establish altermagnets as intrinsic sources of orbital currents and extend orbitronics to symmetry-compensated magnetic systems.

cond-mat.mes-hall↗

arXiv2022

Emulation of Neuron and Synaptic Functions in Spin-Orbit Torque Domain Wall Devices

Neuromorphic computing (NC) architecture has shown its suitability for energy-efficient computation. Amongst several systems, spin-orbit torque (SOT) based domain wall (DW) devices are one of the most energy-efficient contenders for NC. To realize spin-based NC architecture, the computing elements such as synthetic neurons and synapses need to be developed. However, there are very few experimental investigations on DW neurons and synapses. The present study demonstrates the energy-efficient operations of neurons and synapses by using novel reading and writing strategies. We have used a W/CoFeB-based energy-efficient SOT mechanism to drive the DWs at low current densities. We have used the concept of meander devices for achieving synaptic functions. By doing this, we have achieved 9 different resistive states in experiments. We have experimentally demonstrated the functional spike and step neurons. Additionally, we have engineered the anomalous Hall bars by incorporating several pairs, in comparison to conventional Hall crosses, to increase the sensitivity as well as signal-to-noise ratio (SNR). We performed micromagnetic simulations and transport measurements to demonstrate the above-mentioned functionalities.

cond-mat.mes-hall↗

arXiv2022

Diode Like Attributes in Magnetic Domain Wall Devices via Geometrical Pinning for Neuromorphic Computing

Neuromorphic computing (NC) is considered as a potential vehicle for implementing energy-efficient artificial intelligence (AI). To realize NC, several materials systems are being investigated. Among them, the spin-orbit torque (SOT) -driven domain wall (DW) devices are one of the potential candidates. To implement these devices as neurons and synapses, the building blocks of NC, researchers have proposed different device designs. However, the experimental realization of DW device-based NC is only at the primeval stage. In this study, we have proposed and investigated pine-tree-shaped DW devices, based on the Laplace force on the elastic DWs, for achieving the synaptic functionalities. We have successfully observed multiple magnetization states when the DW was driven by the SOT current. The key observation is the asymmetric pinning strength of the device when DW moves in two opposite directions (defined as, xhard and xeasy). This shows the potential of these DW devices as DW diodes. We have used micromagnetic simulations to understand the experimental findings and to estimate the Laplace pressure for various design parameters. The study leads to the path of device fabrication, where synaptic properties are achieved with asymmetric pinning potential.

cond-mat.mes-hall↗

arXiv2021

Nano-engineering the evolution of skyrmion crystal in synthetic antiferromagnets

The evolution of skyrmion crystal encapsulates skyrmion critical behaviors, such as nucleation, deformation and annihilation. Here, we achieve a tunable evolution of artificial skyrmion crystal in nanostructured synthetic antiferromagnet multilayers, which are comprised of perpendicular magnetic multilayers and nanopatterned arrays of magnetic nanodots. The out-of-plane magnetization hysteresis loops and first-order reversal curves show that the nucleation and annihilation of the artificial skyrmion can be controlled by tuning the diameter of and spacing between the nanodots. Moreover, when the bottom layer thickness increases, the annihilation of skyrmion shifts from evolving into a ferromagnetic spin texture to evolving into an antiferromagnetic spin texture. Most significantly, non-volatile multiple states are realized at zero magnetic field via controlling the proportion of the annihilated skyrmions in the skyrmion crystal. Our results demonstrate the tunability and flexibility of the artificial skyrmion platform, providing a promising route to achieve skyrmion-based multistate devices, such as neuromorphic spintronic devices.

cond-mat.str-el↗

arXiv2020

Ultra-low Power Domain Wall Device for Spin-based Neuromorphic Computing

Neuromorphic computing (NC) is gaining wide acceptance as a potential technology to achieve low-power intelligent devices. To realize NC, researchers investigate various types of synthetic neurons and synaptic devices such as memristors and spintronic domain wall (DW) devices. In comparison, DW-based neurons and synapses have potentially higher endurance. However, for realizing low-power devices, DW motion at low energies - typically below pJ/bit - are needed. Here, we demonstrate domain wall motion at current densities as low as 1E6 A/m2 by tailoring the beta-W spin Hall material. With our design, we achieve ultra-low pinning fields and current density reduction by a factor of 10000. The energy required to move the domain wall by a distance of about 20 micrometers is 0.4 fJ, which translates into energy consumption of 0.4 aJ/bit for a bit-length of 20 nm. With a meander domain wall device configuration, we have established a controlled DW motion for synapse applications and have shown the direction to make ultra-low energy spin-based neuromorphic elements.

physics.app-ph↗