Search Results

You searched for all publications:

with publication states 'Published' 'Published (Approved)'
published in journal 'Physical Review B'

Search Again...

These results include publications that have not yet been reviewed and processed by Diamond Light Source. To view only processed publications click here.

You can use the folder icon under Actions to collate papers as required. You can then click on View Folder in the left-hand navigation to review and/or download your folder.

Exact matches
Related results

349 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4, 5, 6, 7, 8 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I05-ARPES	Bulk and surface electronic states in the dosed semimetallic HfTe 2 Zakariae El Youbi , Sungwon Jung , Saumya Mukherjee , Mauro Fanciulli , Jakub Schusser , Olivier Heckmann , Christine Richter , Jan Minar , Karol Hricovini , Matthew D. Watson , Cephise Cacho Physical Review B 101 DOI: 10.1103/PhysRevB.101.235431 Diamond Proposal Number(s): [24921] Open Access Show Abstract ▼ Abstract: The dosing of layered materials with alkali metals has become a commonly used strategy in ARPES experiments. However, precisely what occurs under such conditions, both structurally and electronically, has remained a matter of debate. Here we perform a systematic study of 1T- HfTe 2 , a prototypical semimetal of the transition metal dichalcogenide family. By utilizing photon energy-dependent angle-resolved photoemission spectroscopy (ARPES), we have investigated the electronic structure of this material as a function of potassium (K) deposition. From the k z maps, we observe the appearance of 2D dispersive bands after electron dosing, with an increasing sharpness of the bands, consistent with the wave-function confinement at the topmost layer. In our highest-dosing cases, a monolayerlike electronic structure emerges, presumably as a result of intercalation of the alkali metal. Here, by bringing the topmost valence band below E F , we can directly measure a band overlap of ∼ 0.2 eV. However, 3D bulklike states still contribute to the spectra even after considerable dosing. Our work provides a reference point for the increasingly popular studies of the alkali metal dosing of semimetals using ARPES.	Jun 2020
I05-ARPES	Revealing the single electron pocket of FeSe in a single orthorhombic domain Luke C. Rhodes , Matthew Watson , Amir A. Haghighirad , Daniil V. Evtushinsky , Timur K. Kim Physical Review B 101, 235128 DOI: 10.1103/PhysRevB.101.235128 Diamond Proposal Number(s): [23890] Open Access Show Abstract ▼ Abstract: We measure the electronic structure of FeSe from within individual orthorhombic domains. Enabled by an angle-resolved photoemission spectroscopy beamline with a highly focused beam spot (nano-ARPES), we identify clear stripelike orthorhombic domains in FeSe with a length scale of approximately 1–5 μm. Our photoemission measurements of the Fermi surface and band structure within individual domains reveal a single electron pocket at the Brillouin zone corner. This result provides clear evidence for a one-electron-pocket electronic structure of FeSe, observed without the application of uniaxial strain, and calls for further theoretical insight into this unusual Fermi surface topology. Our results also showcase the potential of nano-ARPES for the study of correlated materials with local domain structures.	Jun 2020
I05-ARPES	Spin structure of spin-orbit split surface states in a magnetic material revealed by spin-integrated photoemission D. Y. Usachov , M. Guttler , S. Schulz , G. Poelchen , S. Seiro , K. Kliemt , K. Kummer , C. Krellner , C. Laubschat , E. V. Chulkov , D. V. Vyalikh Physical Review B 101 DOI: 10.1103/PhysRevB.101.245140 Diamond Proposal Number(s): [18844, 17761] Show Abstract ▼ Abstract: The emergence of ferromagnetism in Rashba systems, where the evolving exchange interaction enters into competition with spin-orbit coupling, leads to a nontrivial spin-polarized electronic landscape with an intricate momentum-dependent spin structure, which is challenging to unveil. Here, we show a way to disentangle the contributions from the effective spin-orbit and exchange fields and thus to gain knowledge of the spin structure in ferromagnetic Rashba materials, which is required for spintronic applications. Our approach is based exclusively on spin-integrated photoemission measurements combined with a two-band modeling. As an example, we consider the mixed-valent material EuIr 2 Si 2 which, while being nonmagnetic in the bulk, reveals strong ferromagnetism at the iridium-silicide surface where both spin-orbit and exchange magnetic interactions coexist. The combined effect of these interactions causes a complex band dispersion of the surface state which can be observed in photoemission experiments. Our method allows us to comprehensively unravel the surface-state spin structure driven by spin-orbit coupling at the ferromagnetic surface. This approach opens up opportunities to characterize the spin structure of ferromagnetic Rashba materials, especially where dedicated spin-resolved measurements remain challenging.	Jun 2020
I05-ARPES I10-Beamline for Advanced Dichroism	Direct observation of the energy gain underpinning ferromagnetic superexchange in the electronic structure of CrGeTe3 Matthew D. Watson , Igor Markovic , Federico Mazzola , Akhil Rajan , Edgar A. Morales , David Burn , Thorsten Hesjedal , Gerrit Van Der Laan , Saumya Mukherjee , Timur K. Kim , Chiara Bigi , Ivana Vobornik , Monica Ciomaga Hatnean , Geetha Balakrishnan , Philip D. C. King Physical Review B 101 DOI: 10.1103/PhysRevB.101.205125 Diamond Proposal Number(s): [21986, 22794, 23785] Show Abstract ▼ Abstract: We investigate the temperature-dependent electronic structure of the van der Waals ferromagnet, CrGeTe3. Using angle-resolved photoemission spectroscopy, we identify atomic- and orbital-specific band shifts upon cooling through TC. From these, together with x-ray absorption spectroscopy and x-ray magnetic circular dichroism measurements, we identify the states created by a covalent bond between the Te 5p and the Cr eg orbitals as the primary driver of the ferromagnetic ordering in this system, while it is the Cr t2g states that carry the majority of the spin moment. The t2g states furthermore exhibit a marked bandwidth increase and a remarkable lifetime enhancement upon entering the ordered phase, pointing to a delicate interplay between localized and itinerant states in this family of layered ferromagnets.	May 2020
I05-ARPES	Signature for non-Stoner ferromagnetism in the van der Waals ferromagnet Fe3GTe2 X. Xu , Y. W. Li , S. R. Duan , S. L. Zhang , Y. J. Chen , L. Kang , A. J. Liang , C. Chen , W. Xia , Y. Xu , P. Malinowski , X. D. Xu , J.-h. Chu , G. Li , Y. F. Guo , Z. K. Liu , L. X. Yang , Y. L. Chen Physical Review B 101 DOI: 10.1103/PhysRevB.101.201104 Diamond Proposal Number(s): [20683] Show Abstract ▼ Abstract: The van der Waals ferromagnet Fe3GeTe2 has attracted great research attention recently due to its extraordinary properties. Here, using high-resolution angle-resolved photoemission spectroscopy, we systematically investigate the temperature evolution of the electronic structure of bulk Fe3GeTe2 . We observe largely dispersive energy bands with exchange splitting that are in overall agreement with our density-functional theory calculation. Interestingly, the band dispersions barely change upon heating towards the ferromagnetic transition near 225 K, except for the reduction of quasiparticle coherence, which strongly deviates from the itinerant Stoner model. We suggest that the local magnetic moments may play a crucial role in the ferromagnetic ordering and the electronic structure of Fe3GeTe2, which will shed light on the generic understanding of itinerant magnetism in correlated materials.	May 2020
I15-Extreme Conditions	Properties and phase diagram of (H2S)2H2 Edward Pace , Xiao-di Liu , Philip Dalladay-simpson , Jack Binns , Miriam Peña-alvarez , J. Paul Attfield , Ross T. Howie , Eugene Gregoryanz Physical Review B 101 DOI: 10.1103/PhysRevB.101.174511 Show Abstract ▼ Abstract: By combining hydrogen and sulfur within diamond-anvil cells we synthesize (H2S)2H2 at 5 GPa and 373 K. Through a series of Raman spectroscopy, infrared spectroscopy, and synchrotron x-ray diffraction experiments we have constrained the phase diagram of (H2S)2H2 within a wide P − T range. On compression we observe the phase transition sequence of I-II-II ′ -III , where II ′ is a previously unreported phase; at room temperature this sequence spans from 5 to 47 GPa, while the application of low temperatures stabilizes this sequence to 127 GPa ( < 80 K ) . Above these pressures we propose that phase III of (H2S)2H2 transforms to a nonmolecular H3S network. Our Raman and infrared measurements indicate that the transition from ( H 2 S ) 2 H 2 to H 3 S is reversible at room temperature. X-ray diffraction reveals that the symmetry of the underlying S lattice of ( H 2 S ) 2 H 2 and H 3 S is retained along this compression path up to at least 135 GPa.	May 2020
I15-Extreme Conditions	High-pressure structural systematics in samarium up to 222 GPa S. E. Finnegan , E. J. Pace , C. V. Storm , M. I. Mcmahon , S. G. Macleod , H.-p. Liermann , K. Glazyrin Physical Review B 101 DOI: 10.1103/PhysRevB.101.174109 Diamond Proposal Number(s): [22350, 20311] Show Abstract ▼ Abstract: Angle-dispersive x-ray powder diffraction experiments have been performed on samarium metal up to 222 GPa. Up to 50 GPa we observe the Sm type (hR9) → dhcp (hP4) → fcc (cF4) → distorted fcc (hR24) → hP3 transition sequence reported previously. The structure of the high-pressure phase above 93 GPa, previously reported as having a monoclinic structure with space group C2/m, is found to be orthorhombic, space group Fddd, with eight atoms per unit cell (oF8 in Pearson notation). This structure is the same as that found in Am, Cm, and Cf at high pressures. Analysis of samarium's equation of state reveals marked changes in compressibility in the hP3 and oF8 phases, with the compressibility of the oF8 phase being that of a “regular” metal.	May 2020
I07-Surface & interface diffraction	Spin splitting and strain in epitaxial monolayer WSe2 on graphene H. Nakamura , A. Mohammed , Ph. Rosenzweig , K. Matsuda , K. Nowakowski , K. Küster , P. Wochner , S. Ibrahimkutty , U. Wedig , H. Hussain , J. Rawle , C. Nicklin , B. Stuhlhofer , G. Cristiani , G. Logvenov , H. Takagi , U. Starke Physical Review B 101 DOI: 10.1103/PhysRevB.101.165103 Diamond Proposal Number(s): [18887] Open Access Show Abstract ▼ Abstract: We present the electronic and structural properties of monolayer WSe 2 grown by pulsed-laser deposition on monolayer graphene (MLG) on SiC. The spin splitting in the WSe 2 valence band at ¯¯¯ K was Δ SO = 0.469 ± 0.008 eV, as determined by angle-resolved photoemission spectroscopy. Synchrotron-based grazing-incidence in-plane x-ray diffraction (XRD) revealed the in-plane lattice constant of monolayer WSe 2 to be a WSe 2 = 3.2757 ± 0.0008 Å. This indicates a lattice compression of − 0.19 % relative to bulk WSe 2 . By using the experimentally determined graphene lattice constant ( a MLG = 2.4575 ± 0.0007 Å), we found that a 3 × 3 unit cell of the slightly compressed WSe 2 is perfectly commensurate with a 4 × 4 graphene lattice with a mismatch below 0.03%, which could explain why the monolayer WSe 2 is compressed on MLG. From XRD and first-principles calculations, we conclude that the observed size of strain will affect Δ SO only on the order of a few meV. In addition, angle-resolved, ultraviolet, and x-ray photoelectron spectroscopies shed light on the band alignment between WSe 2 and MLG/SiC and indicate electron transfer from graphene to the WSe 2 monolayer. As further revealed by atomic force microscopy, the WSe 2 island size depends on the number of carbon layers on top of the SiC substrate. This suggests that the epitaxy of WSe 2 favors the weak van der Waals interactions with graphene, while it is perturbed by the influence of the SiC substrate and its carbon buffer layer.	Apr 2020
I05-ARPES	Three-dimensional electronic structure in ferromagnetic Fe3Sn2 with breathing kagome bilayers Hiroaki Tanaka , Yuita Fujisawa , Kenta Kuroda , Ryo Noguchi , Shunsuke Sakuragi , Cedric Bareille , Barnaby Smith , Cephise Cacho , Sung Won Jung , Takayuki Muro , Yoshinori Okada , Takeshi Kondo Physical Review B 101 DOI: 10.1103/PhysRevB.101.161114 Diamond Proposal Number(s): [24488] Show Abstract ▼ Abstract: A large anomalous Hall effect (AHE) has been observed in ferromagnetic Fe 3 Sn 2 with breathing kagome bilayers. To understand the underlying mechanism for this, we investigate the electronic structure of Fe 3 Sn 2 by angle-resolved photoemission spectroscopy (ARPES). In particular, we use both vacuum ultraviolet light (VUV) and soft x ray (SX), which allow surface-sensitive and relatively bulk-sensitive measurements, respectively, and distinguish bulk states from surface states, which should be unlikely related to the AHE. While VUV-ARPES observes two-dimensional bands mostly due to surface states, SX-ARPES reveals three-dimensional band dispersions with a periodicity of the rhombohedral unit cell in the bulk. Our data show a good consistency with a theoretical calculation based on density functional theory, suggesting a possibility that Fe 3 Sn 2 is a magnetic Weyl semimetal.	Apr 2020
Theoretical Physics	Magnetic skyrmion interactions in the micromagnetic framework R. Brearton , G. Van Der Laan , T. Hesjedal Physical Review B 101, 134422 DOI: 10.1103/PhysRevB.101.134422 Show Abstract ▼ Abstract: Magnetic skyrmions are localized swirls of magnetization with a nontrivial topological winding number. This winding increases their robustness to superparamagnetism and gives rise to a myriad of novel dynamical properties, making them attractive as next-generation information carriers. Recently the equation of motion for a skyrmion was derived using the approach pioneered by Thiele, allowing for macroscopic skyrmion systems to be modeled efficiently. This powerful technique suffers from the prerequisite that one must have a priori knowledge of the functional form of the interaction between a skyrmion and all other magnetic structures in its environment. Here we attempt to alleviate this problem by providing a simple analytic expression that can generate arbitrary repulsive interaction potentials from the micromagnetic Hamiltonian, using it to provide a correction to the interaction between a skyrmion and the boundary of its material. We also discuss a toy model of the radial profile of a skyrmion, which is accurate for a wide range of material parameters.	Apr 2020

Publications Database

Search Results

You searched for all publications:

Search Again...

Subject Areas (check all that apply) select all

Instruments used to collect data (check all that apply) select all

Collaborations involved (check all that apply) select all

Diamond Offline Facilities used

Relevant Technical Areas (check all that apply) select all

Menu for Anonymous User