Research Repository

See what's under the surface


Resonance of terahertz phonons in an acoustic nanocavity (2018)
Journal Article
Sandeep, S., Heywood, S. L., Campion, R. P., Kent, A. J., & Kini, R. N. (2018). Resonance of terahertz phonons in an acoustic nanocavity. Physical Review B, 98(23), doi:10.1103/physrevb.98.235303

We show the resonant behavior of ∼0.5-THz longitudinal acoustic (LA) phonons in an acoustic nanocavity of thickness ∼28 nm sandwiched between two GaAs/AlAs superlattices (SLs). One of the SLs, upon excitation with an ultrafast optical pulse, acts as... Read More

Electrically induced and detected Néel vector reversal in a collinear antiferromagnet (2018)
Journal Article
Godinho, J., Reichlová, H., Kriegner, D., Novák, V., Olejník, K., Kašpar, Z., …Wunderlich, J. (2018). Electrically induced and detected Néel vector reversal in a collinear antiferromagnet. Nature Communications, 9, doi:10.1038/s41467-018-07092-2

Antiferromagnets are enriching spintronics research by many favorable properties that include insensitivity to magnetic fields, neuromorphic memory characteristics, and ultra-fast spin dynamics. Designing memory devices with electrical writing and re... Read More

A high electron mobility phonotransistor (2018)
Journal Article
Poyser, C. L., Li, L. H., Campion, R. P., Akimov, A. V., Linfield, E. H., Davies, A. G., …Kent, A. J. (2018). A high electron mobility phonotransistor. Communications Physics, 1, (1-7). doi:10.1038/s42005-018-0059-7. ISSN 2399-3650

Acoustoelectric devices convert acoustic energy to electrical energy and vice versa. Devices working at much higher acoustic frequencies than those currently available have potential scientific and technological applications, e.g.: as detectors in ph... Read More

Current polarity-dependent manipulation of antiferromagnetic domains (2018)
Journal Article
Wadley, P., Reimers, S., Grzybowski, M., Andrews, C., Wang, M., Chauhan, J., …Jungwirth, T. (in press). Current polarity-dependent manipulation of antiferromagnetic domains. Nature Nanotechnology, 13, doi:10.1038/s41565-018-0079-1. ISSN 1748-3387

Antiferromagnets have several favourable properties as active elements in spintronic devices, including ultra-fast dynamics, zero stray fields and insensitivity to external magnetic fields. Tetragonal CuMnAs is a testbed system in which the antiferro... Read More

Phonon spectroscopy with chirped shear and compressive acoustic pulses (2017)
Journal Article
Poyser, C. L., York, W., Srikanthreddy, D., Glavin, B., Linnik, T., Campion, R., …Kent, A. (in press). Phonon spectroscopy with chirped shear and compressive acoustic pulses. Physical Review Letters, 119, doi:10.1103/PhysRevLett.119.255502. ISSN 0031-9007

Picosecond duration compressive and shear phonon wave packets injected into (311) GaAs slabs transform after propagation through ∼1  mm into chirped acoustic pulses with a frequency increasing in time due to phonon dispersion. By probing the temporal... Read More

Control of antiferromagnetic spin axis orientation in bilayer Fe/CuMnAs films (2017)
Journal Article
Wadley, P., Edmonds, K., Shahedkhah, M., Campion, R., Gallagher, B., Železný, J., …Dhesi, S. (in press). Control of antiferromagnetic spin axis orientation in bilayer Fe/CuMnAs films. Scientific Reports, 7, doi:10.1038/s41598-017-11653-8. ISSN 2045-2322

Using x-ray magnetic circular and linear dichroism techniques, we demonstrate a collinear exchange coupling between an epitaxial antiferromagnet, tetragonal CuMnAs, and an Fe surface layer. A small uncompensated Mn magnetic moment is observed which i... Read More

Antiferromagnetic CuMnAs multi-level memory cell with microelectronic compatibility (2017)
Journal Article
Olejnik, K., Schuler, V., Marti, X., Novák, V., Kaspar, Z., Wadley, P., …Jungwirth, T. (2017). Antiferromagnetic CuMnAs multi-level memory cell with microelectronic compatibility. Nature Communications, 8, doi:10.1038/ncomms15434. ISSN 2041-1723

Antiferromagnets offer a unique combination of properties including the radiation and magnetic field hardness, the absence of stray magnetic fields, and the spin-dynamics frequency scale in terahertz. Recent experiments have demonstrated that relativ... Read More

Imaging current-induced switching of antiferromagnetic domains in CuMnAs (2017)
Journal Article
Grzybowski, M., Wadley, P., Edmonds, K., Beardsley, R., Hills, V. A., Campion, R., …Dhesi, S. (2017). Imaging current-induced switching of antiferromagnetic domains in CuMnAs. Physical Review Letters, 118(5), doi:10.1103/PhysRevLett.118.057701. ISSN 0031-9007

The magnetic order in antiferromagnetic materials is hard to control with external magnetic fields. Using X-ray Magnetic Linear Dichroism microscopy, we show that staggered effective fields generated by electrical current can induce modification of t... Read More

Optical determination of the Néel vector in a CuMnAs thin-film antiferromagnet (2017)
Journal Article
Saidl, V., Němec, P., Wadley, P., Hills, V., Campion, R., Novák, V., …Jungwirth, T. (2017). Optical determination of the Néel vector in a CuMnAs thin-film antiferromagnet. Nature Photonics, 11, doi:10.1038/nphoton.2016.255. ISSN 1749-4885

Recent breakthroughs in electrical detection and manipulation of antiferromagnets have opened a new avenue in the research of non-volatile spintronic devices.1-10 Antiparallel spin sublattices in antiferromagnets, producing zero dipolar fields, lead... Read More

The UK National Quantum Technology Hub in Sensors and Metrology (2016)
Book
Bongs, K., Boyer, V., Cruise, M., Freise, A., Holynski, M., Hughes, J., …John, P. (2016). The UK National Quantum Technology Hub in Sensors and Metrology. In J. Stuhler, & A. J. Shields (Eds.), Quantum opticsSPIE. doi:10.1117/12.2232143

The UK National Quantum Technology Hub in Sensors and Metrology is one of four flagship initiatives in the UK National of Quantum Technology Program. As part of a 20-year vision it translates laboratory demonstrations to deployable practical devices,... Read More

Three-dimensional Heisenberg critical behavior in the highly disordered dilute ferromagnetic semiconductor (Ga,Mn)As (2016)
Journal Article
Wang, M., Marshall, R. A., Edmonds, K. W., Rushforth, A., Campion, R., & Gallagher, B. (2016). Three-dimensional Heisenberg critical behavior in the highly disordered dilute ferromagnetic semiconductor (Ga,Mn)As. Physical Review B, 93, doi:10.1103/PhysRevB.93.184417. ISSN 2469-9950

We present detailed studies of critical behavior in the strongly site-disordered dilute ferromagnetic semiconductor (Ga,Mn)As. (Ga,Mn)As has a low saturation magnetization and relatively strong magnetocrystalline anisotropy. This combination of prop... Read More

Electrical switching of an antiferromagnet (2016)
Journal Article
Wadley, P., Howells, B., Železný, J., Andrews, C., Hills, V., Campion, R., …Jungwirth, T. (2016). Electrical switching of an antiferromagnet. Science, 351(6273), doi:10.1126/science.aab1031. ISSN 0036-8075

Antiferromagnets are hard to control by external magnetic fields because of the alternating directions of magnetic moments on individual atoms and the resulting zero net magnetization. However, relativistic quantum mechanics allows for generating cur... Read More

Intrinsic magnetic refrigeration of a single electron transistor (2016)
Journal Article
Ciccarelli, C., Campion, R., Gallagher, B., & Ferguson, A. (2016). Intrinsic magnetic refrigeration of a single electron transistor. Applied Physics Letters, 108(5), doi:10.1063/1.4941289. ISSN 0003-6951

In this work, we show that aluminium doped with low concentrations of magnetic impurities can be used to fabricate quantum devices with intrinsic cooling capabilities. We fabricate single electron transistors made of aluminium doped with 2% Mn by usi... Read More

Antiferromagnetic structure in tetragonal CuMnAs thin films (2015)
Journal Article
Wadley, P., Hills, V. A., Shahedkhah, M., Edmonds, K., Campion, R., Novák, V., …Jungwirth, T. (2015). Antiferromagnetic structure in tetragonal CuMnAs thin films. Scientific Reports, 5, doi:10.1038/srep17079. ISSN 2045-2322

Tetragonal CuMnAs is an antiferromagnetic material with favourable properties for applications in spintronics. Using a combination of neutron diffraction and x-ray magnetic linear dichroism, we determine the spin axis and magnetic structure in tetrag... Read More

Magnetic coupling in ferromagnetic semiconductor (Ga,Mn)As/(Al,Ga,Mn)As bilayers (2015)
Journal Article
Wang, M., Wadley, P., Campion, R., Rushforth, A., Edmonds, K., Gallagher, B., …Langridge, S. (2015). Magnetic coupling in ferromagnetic semiconductor (Ga,Mn)As/(Al,Ga,Mn)As bilayers. Journal of Applied Physics, 118(5), doi:10.1063/1.4928206. ISSN 0021-8979

We report on a study of ferromagnetic semiconductor (Ga,Mn)As/(Al,Ga,Mn)As bilayers using magnetometry and polarized neutron reflectivity (PNR). From depth-resolved characterization of the magnetic structure obtained by PNR, we concluded that the (Ga... Read More