Hua Chen
Author's posts
Aug 19
Congratulations to Christopher for passing his PhD defense!
Related post on Christopher’s work: When Hall Signals Mislead
May 27
When Hall Signals Mislead
Hall measurements have long been a workhorse in condensed matter physics, offering a simple yet powerful way to probe electronic properties of materials. But as experiments increasingly venture into systems with mesoscopic spatial inhomogeneities, including, e.g., composition, magnetic domains, strain, and various moiré patterns, the interpretation of Hall measurements becomes less straightforward. A common assumption is …
Mar 25
Congratulations to Aidan for passing his PhD defense!
Aidan Winblad at his PhD defense on March 14, 2025. Related post on Aidan’s work: Triangulating Majorana fermions
Mar 12
Physicists Uncover “Hall Mass” Driving Spin Currents Sideways in Advanced Magnets
A team of researchers led by Colorado State University graduate student Luke Wernert and Associate Professor Hua Chen has discovered a new kind of “Hall effect” that could enable more energy-efficient electronic devices. Their findings, published in Physical Review Letters in collaboration with graduate student Bastián Pradenas and Professor Oleg Tchernyshyov at Johns Hopkins University, reveal a …
Jun 19
Triangulating Majorana fermions
Topological quantum computation (TQC) based on Majorana zero modes (MZM) has been actively pursued in the past decade. Aside from well-recognized challenges in unambiguously identifying MZM in existing effective one-dimensional p-wave superconductors, the next step of demonstrating braiding of MZM is even more formidable. The most prevalent proposal on realizing braiding operation is based on …
May 03
Tunneling current-controlled spin states in few-layer van der Waals magnets
The phenomenon of spin-transfer torque in bilayer metallic ferromagnets is well understood in terms of Landau-Lifshitz equation modified by magnetic torques carried by electric currents. However, when each ferromagnet layer is replaced by a single atomic layer of vdW magnetic insulators and electric transport through the bilayer is highly coherent, is the above picture still …
Feb 07
Quantum interference in density wave systems
When hearing “pi-phase” and “quantum oscillations”, would you immediately jump to Berry phase? In a recent collaborative work, we have shown that a new kind of “pi-phase shift”, i.e., that between quantum oscillations in longitudinal resistivities along orthogonal directions, in the prototypical spin density wave material Cr, is caused by quantum interference effects between coupled …
Jan 30
Unexpected symmetry in kagome spin ice revealed by electrical transport
Since the original proposal by Anderson on spin liquid being a possible mechanism for high-Tc superconductivity, electrical transport in frustrated quantum spin systems has always been one of the most enticing topics in condensed matter physics. However, a majority of quantum spin ice and spin liquid candidates are good insulators, making it challenging for standard …
Sep 07
Transporting the shape of spin
Spintronics exploits the idea of using electron spin instead of charge to encode and process information. But can electrons carry more than just spin across diverse materials? Our work answers with a resounding yes, unveiling the transport of spin “shape” in solids. The word “shape” means how spin is distributed spatially about the center of …
Jul 22
An alternative to magnetization
In the ordinary Hall effect, it is the magnetic field that tells which way the electric currents driven by a voltage bias should be deflected, simply through the Lorentz force. In a ferromagnetic conductor, it is the direction of the magnetization that determines that of the transverse anomalous Hall current flow, despite the more complicated …
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