Scientists make breakthrough in quantum materials research

Science Daily  January 31, 2024 Although fine-tuning of topologically protected states in quantum materials holds great promise for novel electronic devices, there are limited methods that allow for the controlled and efficient modulation of the crystal lattice while simultaneously monitoring the changes in the electronic structure within a single sample. A team of researchers in the US (UC Irvine, Los Alamos National Laboratory, University of Tennessee) applied significant and controllable strain to high-quality HfTe5 samples and performed electrical transport measurements to reveal the topological phase transition from a weak topological insulator phase to a strong topological insulator phase. After applying […]

Field-induced superconductivity in quantum materials

Phys.org  December 12, 2023 Field-induced superconductivity is a rare phenomenon where an applied magnetic field enhances or induces superconductivity. A team of researchers in the US (MIT, Argonne National Laboratory, University of Washington, George Mason University) combined tunable uniaxial stress and applied magnetic field on the ferromagnetic superconductor Eu(Fe0.88Co0.12)2As2 to shift the field-induced zero-resistance temperature between 4 K and a record-high value of 10 K. They used x-ray diffraction and spectroscopy measurements under stress and field to reveal that strain tuning of the nematic order and field tuning of the ferromagnetism act as independent control parameters of the superconductivity. Combining […]

Breakthrough in magnetic quantum material paves way for ultra-fast sustainable computers

Nanowerk  April 13, 2023 The discovery of van der Waals (vdW) magnets opened a new paradigm for condensed matter physics and spintronic technologies. However, the operations of active spintronic devices with vdW ferromagnets are limited to cryogenic temperatures, inhibiting their broader practical applications. Researchers in Sweden have demonstrated robust room-temperature operation of lateral spin-valve devices using the vdW itinerant ferromagnet Fe5GeTe2 in heterostructures with graphene. They measured room-temperature spintronic properties of Fe5GeTe2 at the interface with graphene with a negative spin polarization. Lateral spin-valve and spin-precession measurements provided unique insights by probing the Fe5GeTe2/graphene interface spintronic properties via spin-dynamics measurements, […]

The quantum spin liquid that isn’t one

Phys.org  April 18, 2023 For two decades, it was believed that a possible quantum spin liquid was discovered in a synthetically produced material. In this case, it would not follow the laws of classical physics even on a macroscopic level, but rather those of the quantum world. An international team of researchers (Austria, Spain) has shown that the promising material, κ-(BEDT-TTF)2Cu2(CN)3, is not the predicted quantum spin liquid, but a material that can be described using known concepts. They were able to precisely map the spin-gapped phase through the Mott transition by ultrahigh-resolution strain tuning. Through transport experiments they revealed […]

Electrical gating of the charge-density-wave quantum phases opens innovative electronic applications

Nanowerk  November 1, 2022 Recent years witnessed a rebirth of the field of CDW materials and devices, partially driven by an interest in layered quasi-2D van der Waals materials where CDW phases can manifest themselves at room temperature. Despite numerous attempts, the electrical gating of the CDW phase, which is needed for many practical applications, remained elusive. An international team of researchers (USA – UC Riverside, University of Georgia, Poland) has demonstrated the electrical gating of the charge-density-wave phases and current in h-BN-capped three-terminal 1T-TaS2 heterostructure devices. The evolution of the hysteresis and the presence of abrupt spikes in the […]

Physicists probe ‘astonishing’ morphing properties of honeycomb-like material

Science Daily  October 12, 2022 A team of researchers in the US (University of Colorado, Georgia Institute of Technology, Oak Ridge National Laboratory, University of Kentucky) synthesized a quantum material which has the chemical formula Mn3Si2Te6 and has “honeycomb” structure because its manganese and tellurium atoms form a network of interlocking octahedra that look like the cells in a beehive. Under most circumstances, it behaved a lot like an insulator. When it was exposed to magnetic fields in a certain way, it suddenly morphed from rubber into metal in behavior. The team explained this behavior as an exotic quantum state […]

Unique quantum material could enable ultra-powerful, compact computers

Phys.org  May 20, 2022 A long-standing challenge has been to realize materials that integrate and connect tunable electrical transport and tunable spin configurations. Two-dimensional materials offer a platform to realize this concept but known 2D magnetic semiconductors are electrically insulating in their magnetic phase. An international team of researchers (USA – Columbia University, Brookhaven National Laboratory, Oak Ridge National Laboratory, Washington University, Japan) demonstrated tunable electron transport within the magnetic phase of the 2D semiconductor chromium sulfide bromide (CrSBr) and showed strong coupling between its magnetic order and charge transport. Exploiting the sensitivity of magnetoresistance to magnetic order, they uncovered […]

A simpler approach for creating quantum materials

Phys.org  May 4, 2022 Using twisted bilayer graphene to make devices remains challenging because of the low yield of fabricating twisted bilayer graphene. Researchers at the University of Pennsylvania have shown how patterned, periodic deformations of a single layer of graphene transforms it into a material with electronic properties previously seen in twisted graphene bilayers. To better understand the quantum geometrical properties of this system, they set out to understand the theory underlying how electrons move in this single-layered system. After running computer simulations of single-layered experiments, the researchers were surprised to find new evidence of unexpected phenomena along the […]

Lasers trigger magnetism in atomically thin quantum materials

Science  Daily  April 20, 2022 Recently two-dimensional moiré superlattices have emerged as a promising platform for quantum engineering. The power of the moiré system lies in the high tunability of its physical parameters by adjusting the layer twist angle, electrical field, moiré carrier filling and interlayer coupling. An international team of researchers (USA – University of Washington, Oak Ridge National Laboratory, Pacific Northwest National Laboratory, Hong Kong, Japan) found that optical excitation can highly tune the spin–spin interactions between moiré-trapped carriers, resulting in ferromagnetic order in WS2 /WSe2 moiré superlattices. Near the filling factor of −1/3, as the excitation power […]

Scientists find ‘knob’ to control magnetic behavior in quantum material

Science Daily  April 12, 2022 A key to unlocking new functionalities in quantum materials is the discovery of tunable coupling between spins and other microscopic degrees of freedom. A team of researchers in the US (Pennsylvania State University, University, UC San Diego, Northwestern University SLAC National Accelerator Laboratory, Argonne National Laboratory, Stanford University) has found evidence for interlayer magnetophononic coupling in the layered magnetic topological insulator MnBi2Te4. They observed anomalies in phonon scattering intensities across magnetic field-driven phase transitions, despite the absence of discernible static structural changes. This behavior is a consequence of a magnetophononic wave-mixing process that allows for […]