Co K-edge magnetic circular dichroism across the spin state transition in LaCoO3 single crystal


V Efimov, A Ignatov, IO Troyanchuk, VV Sikolenko, A Rogalev, F Wilhelm, E Efimova, SI Tiutiunnikov, D Karpinsky, V Kriventsov, E Yakimchuk, S Molodtsov, P Sainctavit, D Prabhakaran, IOP

Step-Flow Growth of Bi2Te3 Nanobelts

CRYSTAL GROWTH & DESIGN 16 (2016) 6961-6966

P Schonherr, T Tilbury, H Wang, AA Haghighirad, V Srot, PA van Aken, T Hesjedal

Distinct Electronic Structure for the Extreme Magnetoresistance in YSb.

Physical review letters 117 (2016) 267201-

J He, C Zhang, NJ Ghimire, T Liang, C Jia, J Jiang, S Tang, S Chen, Y He, S-K Mo, CC Hwang, M Hashimoto, DH Lu, B Moritz, TP Devereaux, YL Chen, JF Mitchell, Z-X Shen

An extreme magnetoresistance (XMR) has recently been observed in several nonmagnetic semimetals. Increasing experimental and theoretical evidence indicates that the XMR can be driven by either topological protection or electron-hole compensation. Here, by investigating the electronic structure of a XMR material, YSb, we present spectroscopic evidence for a special case which lacks topological protection and perfect electron-hole compensation. Further investigations reveal that a cooperative action of a substantial difference between electron and hole mobility and a moderate carrier compensation might contribute to the XMR in YSb.

Modulated spin helicity stabilized by incommensurate orbital density waves in a quadruple perovskite manganite

PHYSICAL REVIEW B 93 (2016) ARTN 180403

RD Johnson, DD Khalyavin, P Manuel, A Bombardi, C Martin, LC Chapon, PG Radaelli

Fermi-surface topologies and low-temperature phases of the filled skutterudite compounds CeOs4Sb12 and NdOs4Sb12

PHYSICAL REVIEW B 94 (2016) ARTN 205140

PC Ho, J Singleton, PA Goddard, FF Balakirev, S Chikara, T Yanagisawa, MB Maple, DB Shrekenhamer, X Lee, AT Thomas

Magnetic properties of Sr3NiIrO6 and Sr3CoIrO6: Magnetic hysteresis with coercive fields of up to 55 T

PHYSICAL REVIEW B 94 (2016) ARTN 224408

J Singleton, JW Kim, CV Topping, A Hansen, E-D Mun, S Chikara, I Lakis, S Ghannadzadeh, P Goddard, X Luo, YS Oh, S-W Cheong, VS Zapf

Coherent Magnetoelastic Domains in Multiferroic BiFeO_{3} Films.

Physical review letters 117 (2016) 177601-

N Waterfield Price, RD Johnson, W Saenrang, F Maccherozzi, SS Dhesi, A Bombardi, FP Chmiel, C-B Eom, PG Radaelli

The physical properties of epitaxial films can fundamentally differ from those of bulk single crystals even above the critical thickness. By a combination of nonresonant x-ray magnetic scattering, neutron diffraction and vector-mapped x-ray magnetic linear dichroism photoemission electron microscopy, we show that epitaxial (111)-BiFeO_{3} films support submicron antiferromagnetic domains, which are magnetoelastically coupled to a coherent crystallographic monoclinic twin structure. This unique texture, which is absent in bulk single crystals, should enable control of magnetism in BiFeO_{3} film devices via epitaxial strain.

Imaging and manipulation of skyrmion lattice domains in Cu2OSeO3


SL Zhang, A Bauer, H Berger, C Pfleiderer, G van der Laan, T Hesjedal

Magnetic ordering in Ho-doped Bi2Te3 topological insulator thin films


AI Figueroa, SE Harrison, LJ Collins-McIntyre, G van der Laan, T Hesjedal

Ab initio cycloidal and chiral magnetoelectric responses in Cr2O3

PHYSICAL REVIEW B 94 (2016) ARTN 100405

N Tillack, JR Yates, PG Radaelli

Quantum Interference in Graphene Nanoconstrictions.

Nano letters 16 (2016) 4210-4216

P Gehring, H Sadeghi, S Sangtarash, CS Lau, J Liu, A Ardavan, JH Warner, CJ Lambert, GAD Briggs, JA Mol

We report quantum interference effects in the electrical conductance of chemical vapor deposited graphene nanoconstrictions fabricated using feedback controlled electroburning. The observed multimode Fabry-Pérot interferences can be attributed to reflections at potential steps inside the channel. Sharp antiresonance features with a Fano line shape are observed. Theoretical modeling reveals that these Fano resonances are due to localized states inside the constriction, which couple to the delocalized states that also give rise to the Fabry-Pérot interference patterns. This study provides new insight into the interplay between two fundamental forms of quantum interference in graphene nanoconstrictions.

Magnetic phase diagram of La2−xSrxCoO4 revised using muon-spin relaxation

Physical Review B - Condensed Matter and Materials Physics American Physical Society (2016)

RC Williams, F Xiao, T Lancaster, R De Renzi, G Allodi, S Bordignon, PG Freeman, FL Pratt, SR Giblin, JS Moeller, SJ Blundell, AT Boothroyd, D Prabhakaran

Intermediate magnetization state and competing orders in Dy2Ti2O7 and Ho2Ti2O7.

Nature communications 7 (2016) 12592-

RA Borzi, FA Gómez Albarracín, HD Rosales, GL Rossini, A Steppke, D Prabhakaran, AP Mackenzie, DC Cabra, SA Grigera

Among the frustrated magnetic materials, spin-ice stands out as a particularly interesting system. Residual entropy, freezing and glassiness, Kasteleyn transitions and fractionalization of excitations in three dimensions all stem from a simple classical Hamiltonian. But is the usual spin-ice Hamiltonian a correct description of the experimental systems? Here we address this issue by measuring magnetic susceptibility in the two most studied spin-ice compounds, Dy2Ti2O7 and Ho2Ti2O7, using a vector magnet. Using these results, and guided by a theoretical analysis of possible distortions to the pyrochlore lattice, we construct an effective Hamiltonian and explore it using Monte Carlo simulations. We show how this Hamiltonian reproduces the experimental results, including the formation of a phase of intermediate polarization, and gives important information about the possible ground state of real spin-ice systems. Our work suggests an unusual situation in which distortions might contribute to the preservation rather than relief of the effects of frustration.

Unconventional magnetism on a honeycomb lattice in alpha-RuCl3 studied by muon spin rotation

PHYSICAL REVIEW B 94 (2016) ARTN 020407

F Lang, PJ Baker, AA Haghighirad, Y Li, D Prabhakaran, R Valenti, SJ Blundell

Quantum Electronics: Evidence of Both Surface and Bulk Dirac Bands and Anisotropic Nonsaturating Magnetoresistance in ZrSiS (Adv. Electron. Mater. 10/2016)

Advanced Electronic Materials 2 (2016)

X Wang, X Pan, M Gao, J Yu, J Jiang, J Zhang, H Zuo, M Zhang, Z Wei, W Niu, Z Xia, X Wan, Y Chen, F Song, Y Xu, B Wang, G Wang, R Zhang

Ordering Gold Nanoparticles with DNA Origami Nanoflowers.

ACS nano 10 (2016) 7303-7306

R Schreiber, I Santiago, A Ardavan, AJ Turberfield

Nanostructured materials, including plasmonic metamaterials made from gold and silver nanoparticles, provide access to new materials properties. The assembly of nanoparticles into extended arrays can be controlled through surface functionalization and the use of increasingly sophisticated linkers. We present a versatile way to control the bonding symmetry of gold nanoparticles by wrapping them in flower-shaped DNA origami structures. These "nanoflowers" assemble into two-dimensonal gold nanoparticle lattices with symmetries that can be controlled through auxiliary DNA linker strands. Nanoflower lattices are true composites: interactions between the gold nanoparticles are mediated entirely by DNA, and the DNA origami will fold into its designed form only in the presence of the gold nanoparticles.

Dramatically decreased magnetoresistance in non-stoichiometric WTe2 crystals

Scientific Reports 6 (2016)

Y-Y Lv, B-B Zhang, X Li, B Pang, F Zhang, D-J Lin, J Zhou, S-H Yao, YB Chen, S-T Zhang, M Lu, Z Liu, Y Chen, Y-F Chen

Multidomain Skyrmion Lattice State in Cu2OSeO3.

Nano letters 16 (2016) 3285-3291

SL Zhang, A Bauer, DM Burn, P Milde, E Neuber, LM Eng, H Berger, C Pfleiderer, G van der Laan, T Hesjedal

Magnetic skyrmions in chiral magnets are nanoscale, topologically protected magnetization swirls that are promising candidates for spintronics memory carriers. Therefore, observing and manipulating the skyrmion state on the surface level of the materials are of great importance for future applications. Here, we report a controlled way of creating a multidomain skyrmion state near the surface of a Cu2OSeO3 single crystal, observed by soft resonant elastic X-ray scattering. This technique is an ideal tool to probe the magnetic order at the L3 edge of 3d metal compounds giving an average depth sensitivity of ∼50 nm. The single-domain 6-fold-symmetric skyrmion lattice can be broken up into domains, overcoming the propagation directions imposed by the cubic anisotropy by applying the magnetic field in directions deviating from the major cubic axes. Our findings open the door to a new way to manipulate and engineer the skyrmion state locally on the surface or on the level of individual skyrmions, which will enable applications in the future.

Transverse field muon-spin rotation measurement of the topological anomaly in a thin film of MnSi

PHYSICAL REVIEW B 93 (2016) ARTN 140412

T Lancaster, F Xiao, Z Salman, IO Thomas, SJ Blundell, FL Pratt, SJ Clark, T Prokscha, A Suter, SL Zhang, AA Baker, T Hesjedal

Experimental and density functional study of Mn doped Bi2Te3 topological insulator

APL MATERIALS 4 (2016) ARTN 126103

A Ghasemi, D Kepaptsoglou, AI Figueroa, GA Naydenov, PJ Hasnip, MIJ Probert, Q Ramasse, G van der Laan, T Hesjedal, VK Lazarov