65 citations · 136 across the 12 of their papers we have counts for
13 papers
Theory of extrinsic contributions to the full orbital current
James H Cullen, Dimitrie Culcer
The orbital Hall effect (OHE) underpins the emerging field of orbitronics. A complete quantum-mechanical evaluation of the usual orbital-current operator must retain all matrix ele…
Inter-band coherence effects in disordered crystals: beyond the non-crossing approximation
Zhanning Wang, James H. Cullen, Roberto Raimondi +1
We develop a quantum kinetic theory for Bloch electrons driven by a uniform dc electric field, extending the nonequilibrium density-matrix formalism beyond the non-crossing approxi…
Ge as an orbitronic platform: giant in-plane orbital magneto-electric effect in a 2-dimensional hole gas
James H. Cullen, Dimitrie Culcer
Increasing demand for computational power has initiated the hunt for energy efficient and stable memory devices. This is the overarching motivation behind the recent rise of \texti…
Orbital Hall effect in spin-3/2 hole-doped semiconductors and its implications for orbitronics
James H. Cullen, Zhanning Wang, Dimitrie Culcer
State-of-the-art magnetic devices rely on faster, more efficient memory elements. A major recent advance is the discovery of orbital torques, which use the orbital angular momentum…
Quantum geometry and quantum capacitance in the orbital magneto-electric effect
James H. Cullen, Daniel P. Arovas, Roberto Raimondi +1
The orbital magneto-electric effect (OME), the generation of a steady-state orbital angular momentum (OAM) density by an electric field, is a central component of orbitronics. Neve…
Giant orbital Hall effect due to the bulk states of 3D topological insulators
James H. Cullen, Hong Liu, Dimitrie Culcer
The highly efficient torques generated by 3D topological insulators make them a favourable platform for faster and more efficient magnetic memory devices. Recently, research into h…
Quantum correction to the orbital Hall effect
Hong Liu, James H. Cullen, Daniel P. Arovas +1
Evaluations of the orbital Hall effect (OHE) have only retained inter-band matrix elements of the position operator. Here we evaluate the OHE including all matrix elements of the p…
Spin-Hall effect in topological materials: Evaluating the proper spin current in systems with arbitrary degeneracies
Hongyang Ma, James H. Cullen, Serajum Monir +2
The spin-Hall effect underpins some of the most active topics in modern physics, including spin torques and the inverse spin-Hall effect, yet it lacks a proper theoretical descript…
Spin-Hall effect due to the bulk states of topological insulators: Extrinsic contribution to the conserved spin current
James H. Cullen, Dimitrie Culcer
The substantial amount of recent research into spin torques has been accompanied by a revival of interest in the spin-Hall effect. This effect contributes to the spin torque in man…
Topological nature of the proper spin current and the spin-Hall torque
Hong Liu, James H. Cullen, Dimitrie Culcer
Spin currents are key to spin torque devices, but determining the proper spin current is non-trivial. Here we derive a general quantum-mechanical formula for the intrinsic proper s…
Spin-orbit torques due to topological insulator surface states: an in-plane magnetization as a probe of extrinsic spin-orbit scattering
Mohsen Farokhnezhad, James H. Cullen, Dimitrie Culcer
Topological insulator (TI) surface states exert strong spin-orbit torques. When the magnetization is in the plane its interaction with the TI conduction electrons is non-trivial, a…
Spin transfer torques due to the bulk states of topological insulators
James H. Cullen, Rhonald Burgos Atencia, Dimitrie Culcer
Spin torques at topological insulator (TI)/ferromagnet interfaces have received considerable attention in recent years with a view towards achieving full electrical manipulation of…
Generating a topological anomalous Hall effect in a non-magnetic conductor
James H. Cullen, Pankaj Bhalla, Elizabeth Marcellina +2
The ordinary Hall effect is driven by the Lorentz force, while its anomalous counterpart occurs in ferromagnets. Here we show that the Berry curvature monopole of non-magnetic 2D s…