Article
Materials Science, Multidisciplinary
Long Qian, Kelly Neubauer, Joshua Miller, Yuxiang Gao, Jordan Murley, Songxue Chi, Shiming Lei, Pengcheng Dai
Summary: YbRh3Si7 is a unique heavy fermion compound with relatively high magnetic ordering temperature and large Yb-Yb distance. By doping Co into YbRh3Si7, the ferromagnetic ordering temperature can be significantly increased, and a crossover from antiferromagnetic to ferromagnetic order is observed. Specific heat and magnetotransport measurements confirm the heavy fermion behavior and persistence of Kondo latticelike behavior in the Yb(Rh1-xCox)3Si7 series.
Article
Chemistry, Physical
Diego S. Evaristo, Rai F. Juca, Joao M. Soares, Rodolfo B. Silva, Gilberto D. Saraiva, Robert S. Matos, Nilson S. Ferreira, Marco Salerno, Marcelo A. Macedo
Summary: Iron niobates, both pure and substituted with copper, were studied for their structural and magnetic properties. Copper ions were found to have high solubility in the structure and resulted in better structural stability. The insertion of Cu2+ ions caused an antiferromagnetic-ferromagnetic transition, leading to a weak ferromagnetic order. This transition is likely due to the increase in super-exchange interactions between Fe/Cu ions and the formation of bound magnetic polarons in the oxygen vacancies.
Article
Chemistry, Multidisciplinary
Qile Li, Chi Xuan Trang, Weikang Wu, Jinwoong Hwang, David Cortie, Nikhil Medhekar, Sung-Kwan Mo, Shengyuan A. Yang, Mark T. Edmonds
Summary: Combining magnetism and nontrivial band topology can achieve the quantum anomalous Hall (QAH) effect at high temperatures for lossless transport applications. In this study, a heterostructure consisting of two single-septuple layers (1SL) of MnBi2Te4, an ultrathin few quintuple layer (QL) Bi2Te3, and another 1SL MnBi2Te4 was grown via molecular beam epitaxy. The electronic structure was probed using angle-resolved photoelectron spectroscopy, and strong hexagonally warped massive Dirac fermions and a bandgap of 75 +/- 15 meV were observed. The magnetic origin of the gap was confirmed, and these findings provide insights into magnetic proximity effects in topological insulators and a promising platform for realizing the QAH effect at elevated temperatures.
ADVANCED MATERIALS
(2022)
Article
Physics, Multidisciplinary
A. Scheie, O. Benton, M. Taillefumier, L. D. C. Jaubert, G. Sala, N. Jalarvo, S. M. Koohpayeh, N. Shannon
Summary: In this study, the dynamical properties of Yb2Ti2O7 are explored using inelastic neutron scattering. It is found that spin correlations exhibit dynamic scaling behavior, similar to that found near a quantum critical point. The observed scaling collapse is explained within a phenomenological theory of multiple-phase competition, and is also confirmed in semiclassical simulations of a microscopic model of Yb2Ti2O7.
PHYSICAL REVIEW LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Xiyun Li, Xin Wang, Zhen Wu, Wen-Xing Yang, Aixi Chen
Summary: This study investigates the characteristics of tunable magnon antibunching in a hybrid ferromagnet-superconductor system, showing that both CMB and UMB can coexist and be regulated simultaneously in the strong coupling regime. Adjusting the magnon-qubits coupling strength ratio and qubits detuning ratio has a significant impact on antibunching effect against thermal magnon excitation.
Article
Chemistry, Multidisciplinary
Yue Li, Frank Barrows, Arthur R. C. McCray, Timothy Cote, David Friedman, Ralu N. S. Divan, Amanda K. Petford-Long, Charudatta Phatak
Summary: Artificial spin ices composed of coupled nanomagnets offer the possibility to create designer geometrical frustration and manipulate inter-nanomagnet interactions. In this study, a dimer kagome artificial spin ice system was created and the antiferromagnetic order was controlled by tuning lattice geometry. Monte Carlo simulations were used to analyze the behavior of the system and different antiferromagnetic phases and interactions were visualized in demagnetized lattices with different lattice parameters.
CELL REPORTS PHYSICAL SCIENCE
(2022)
Article
Physics, Applied
Xiangqi Wang, Jun Tan
Summary: Lifshitz transition leads to a change in the Fermi level and provides an opportunity to study the relationship between Fermi-surface topology and Berry curvature. In LiMn6Sn6, a ferromagnetic Kagome-lattice material, we observed a switch from extrinsic to intrinsic anomalous Hall effect around a Lifshitz transition. The Lifshitz transition is manifested by a flip in the ordinary Hall resistivity, indicating a significant change in the Fermi surface topology.
APPLIED PHYSICS LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Anirban Chakraborty, Abhay K. Srivastava, Ankit K. Sharma, Ajesh K. Gopi, Katayoon Mohseni, Arthur Ernst, Hakan Deniz, Binoy Krishna Hazra, Souvik Das, Paolo Sessi, Ilya Kostanovskiy, Tianping Ma, Holger L. Meyerheim, Stuart S. P. Parkin
Summary: Researchers have observed chiral Neel skyrmions in the ferromagnetic compound Fe3GeTe2, which lacks inversion symmetry due to an asymmetric distribution of Fe vacancies. They also found that the size of the skyrmions in FGT depends on its thickness.
ADVANCED MATERIALS
(2022)
Article
Astronomy & Astrophysics
Yann Cado, Mariano Quiros
Summary: We study a modification of the Higgs inflation scenario by introducing an extra scalar field phi, which is coupled to the Ricci scalar and mixed with the Higgs field h. By coupling phi to the Chern-Simons term, helical magnetic fields are generated during inflation. This model can solve the instability problem of the Standard Model and predicts modifications that can be explored at future colliders.
Article
Materials Science, Multidisciplinary
Hisato Komatsu, Yoshihiko Nonomura, Masamichi Nishino
Summary: In this study, we investigate the field-temperature phase diagram of a two-dimensional dipolar Ising ferromagnet on a kagome lattice with a specific exchange-to-dipolar constant ratio of ?? = 1 using the stochastic cutoff O(N) Monte Carlo method. We calculate order parameters and thermodynamic quantities for stripe and bubble phases. We discover two types of stripe phases with varying arrangement of branch spins neighboring the stripe frame at low fields, and two bubble phases with a regular triangular lattice of three-spin domains (bubbles) that change on the kagome lattice at high fields. We also observe the presence of a disordered phase between stripe and bubble phases, as well as between the two bubble phases with increasing field.
Article
Multidisciplinary Sciences
D. Bromley, A. J. Wright, L. A. H. Jones, J. E. N. Swallow, T. Beesley, R. Batty, R. S. Weatherup, V. R. Dhanak, L. O'Brien
Summary: This study reports on the electronic and magnetic properties of superconductor-ferromagnet heterostructures fabricated on unheated thermally oxidised Si substrates. The results show that polycrystalline Nb thin films have reliable high superconducting critical temperatures, and these properties are improved during ex-situ annealing.
SCIENTIFIC REPORTS
(2022)
Article
Nanoscience & Nanotechnology
Wen Wan, Rishav Harsh, Paul Dreher, Fernando de Juan, Miguel M. Ugeda
Summary: Chemical substitution is a promising approach to explore collective phenomena in low-dimensional quantum materials. Transition metal dichalcogenide alloys are shown to be ideal platforms for this purpose. We demonstrate the emergence of superconductivity in single-layer TaSe2 through minute electron doping using substitutional W atoms. The temperature and magnetic field dependence of the superconducting state of Ta1-delta W delta Se2 are investigated using scanning tunneling spectroscopy. A superconducting dome spanning 0.003 < delta < 0.03 with a maximized critical temperature of 0.9 K is observed, which is significantly higher than that of bulk TaSe2 (T-C = 0.14 K). The superconductivity is attributed to an increase in density of states as the Fermi surface approaches a van Hove singularity, but gradually weakens as the singularity is reached, shaping the superconducting dome. Doping-dependent measurements suggest the development of a Coulomb glass phase triggered by disorder due to W dopants.
NPJ 2D MATERIALS AND APPLICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Chenhui Zhang, Chen Liu, Senfu Zhang, Bojian Zhou, Chaoshuai Guan, Yinchang Ma, Hanin Algaidi, Dongxing Zheng, Yan Li, Xin He, Junwei Zhang, Peng Li, Zhipeng Hou, Gen Yin, Kai Liu, Yong Peng, Xi-Xiang Zhang
Summary: This article reports the observation of dipole skyrmions with unconventional helicity polarization in a van der Waals ferromagnet, Fe5-delta GeTe2. Experimental evidence demonstrates that short-range superstructures in Fe5-delta GeTe2 lead to helicity polarization, which is caused by a localized DMI contribution that breaks the degeneracy of opposite helicities.
ADVANCED MATERIALS
(2022)
Article
Multidisciplinary Sciences
Andreas Wendl, Heike Eisenlohr, Felix Rucker, Christopher Duvinage, Markus Kleinhans, Matthias Vojta, Christian Pfleiderer
Summary: This study reports the magnetic susceptibility of LiHoF4 near a transverse-field quantum critical point and reveals a new type of phase transition called mesoscale quantum criticality. The results show that the observed mesoscale pattern formation in the surroundings of quantum phase transitions is in excellent agreement with the theoretical predictions. These findings provide valuable insights into the understanding of mesoscale patterns in the vicinity of quantum phase transitions.
Article
Materials Science, Multidisciplinary
Y. V. Piskunov, A. F. Sadykov, V. V. Ogloblichev, A. G. Smolnikov, A. P. Gerashenko, P. Z. Si
Summary: In this study, Cr-53 NMR measurements were performed to investigate the static and dynamic properties of a half-metallic ferromagnet CrO2. Two magnetically nonequivalent Cr nuclei were observed in the ferromagnetic phase, despite all of the Cr ions being situated on the crystallographic equivalent sites. The temperature dependence of the Cr-53 spin-lattice relaxation rate was measured and it was found that the relaxation of nuclear magnetic moments is influenced by both orbital contribution and three-magnon processes.
Article
Multidisciplinary Sciences
M. J. Pearce, K. Goetze, A. Szabo, T. S. Sikkenk, M. R. Lees, A. T. Boothroyd, D. Prabhakaran, C. Castelnovo, P. A. Goddard
Summary: Magnetically frustrated systems exhibit complex behavior such as emergent symmetries, topological properties, and exotic excitations, with the reliable experimental indicator of the density of magnetic monopoles remaining elusive despite extensive research. This study demonstrates a strong coupling between monopoles on the holmium sublattice and antiferromagnetically ordered iridium ions, paving the way for a quantitative experimental measure of monopole density. Furthermore, the research showcases the ability to control antiferromagnetic domain walls using a uniform external magnetic field, a crucial step towards enhancing future spintronic device design.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Physical
Manpreet Kaur, Marc Walker, Steven Hindmarsh, Charlotte Bolt, Stephen York, Yisong Han, Martin R. Lees, Katharina Brinkert
Summary: Efficient artificial photosynthesis systems use catalyst- and surface-functionalized photovoltaic devices to perform photoelectrochemical water oxidation, CO2 recycling, and hydrogen generation. This research focuses on developing photoelectrodeposition procedures to directly deposit mixed-metal electrocatalyst nanostructures on semiconductor surfaces for light-assisted dinitrogen activation. The electrocatalyst films fabricated through this process exhibit different physical properties and are largely nitrogen-free, which is challenging to achieve using traditional deposition techniques. Initial measurements and XPS studies confirm the successful activation of dinitrogen using these electrocatalyst coatings.
FARADAY DISCUSSIONS
(2023)
Article
Chemistry, Multidisciplinary
Stephen E. Brown, Ioanna Mantaloufa, Ryan T. Andrews, Thomas J. Barnes, Martin R. Lees, Frank De Proft, Ana V. Cunha, Sebastian D. Pike
Summary: The molecular titanium-oxo cluster [Ti6O6((OPr)-Pr-i)(6)((O2CBu)-Bu-t)(6)] (1) can be activated by UV light to produce a mixed valent (photoreduced) Ti (iii/iv) cluster, along with alcohol and ketone organic products. Mechanistic studies show a two-electron mechanism utilizing the cluster structure for multielectron reactions. The photoreduced products [Ti6O6((OPr)-Pr-i)(4)((O2CBu)-Bu-t)(6)(sol)(2)] can be isolated and characterized, and undergo onward oxidation under air. The redox reactivity described is only possible in a cluster with multiple Ti sites.
Article
Chemistry, Multidisciplinary
Robyn E. Powell, Martin R. Lees, Graham J. Tizzard, Simon J. Coles, Qingchun Yuan, Petra J. van Koningsbruggen
Summary: The synthesis and crystal structure (100 K) of the compound [(CH3)(2)NH2]-[Fe(C10H11O2N3S)(2)] are reported. The structure consists of an octahedral [Fe-III (L)(2)](-) fragment and a dimethylammonium cation. Each L2- ligand binds to the FeIII ion through the S, N, and O atoms, forming an (FeS2N2O2)-S-III chromophore. The ligands are arranged in two perpendicular planes, with the O and S atoms in cis positions and the N atoms in trans positions. The magnetic measurements confirm the presence of a high-spin Fe-III ion with D = 0.83 (1) cm(-1) and g = 2 at 100 K.
ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Kunya Yang, Hong Wu, Zefang Li, Chen Ran, Xiao Wang, Fengfeng Zhu, Xiangnan Gong, Yan Liu, Guiwen Wang, Long Zhang, Xinrun Mi, Aifeng Wang, Yisheng Chai, Yixi Su, Wenhong Wang, Mingquan He, Xiaolong Yang, Xiaoyuan Zhou
Summary: By combining thermal transport measurements with density functional theory calculations, this study demonstrates low thermal conductivity (kappa) of approximately 1 W m(-1) K-1 in a typical layered van der Waals ferromagnet Cr2Si2Te6. The low kappa is attributed to the spin-phonon scattering and resonant magnon-phonon scattering, which can be strongly suppressed by magnetic fields. The theoretical approach used in this study may provide a generic understanding of spin-phonon scattering in various systems.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Engineering, Environmental
Sayan Pal, Maximilian O. Besenhard, Liudmyla Storozhuk, Martin R. Lees, Nguyen Thi Kim Thanh, Asterios Gavriilidis
Summary: This work demonstrates a modular triphasic flow reactor platform that enables continuous and fouling-free four-step co-precipitation flow synthesis of iron oxide nanoparticles (IONPs) for magnetically induced hyperthermia cancer treatment (MHCT). By using a seeded growth co-precipitation strategy and a nitrogen gas spacer, the flow platform allows for the continuous synthesis of colloidally stable IONPs with high heating performance in a short residence time.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Chemistry, Inorganic & Nuclear
Lu Jia, Matthew D. Lloyd, Martin R. Lees, Limin Huang, Richard I. Walton
Summary: In this study, the crystallization of a new series of A-site substituted lanthanum ferrite materials (La1-xREx)FeO3 was explored using hydrothermal method. The effect of elemental substitution on the morphological, structural, and magnetic properties of the materials was studied. It was found that homogeneous solid solutions are formed when La3+ and substituent ions have similar radii, while crystallization in separate phases is found when there is a large radius difference. A-site replacement induces an evolution in the crystallite shape, providing evidence for a phase-separation-driven evolution of morphology.
INORGANIC CHEMISTRY
(2023)
Article
Materials Science, Multidisciplinary
Amelia E. Hall, Pascal Manuel, Dmitry D. Khalyavin, Fabio Orlandi, Daniel A. Mayoh, Lieh-Jeng Chang, Yu-Sheng Chen, David G. C. Jonas, Martin R. Lees, Geetha Balakrishnan
Summary: The Mn3XY family of materials, with ordered chiral beta-Mn structure, displays different magnetic behaviors, with Mn3RhGe exhibiting a high-temperature incommensurate magnetic structure transitioning into a noncollinear commensurate antiferromagnetic ground state, while Mn3IrSi shows a noncollinear commensurate magnetic structure at all temperatures.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Ching -Yu Huang, Sing-Hong Chan, Ying-Jer Kao, Pochung Chen
Summary: We propose a scheme to perform finite-size scaling analysis for two-dimensional classical models using tensor network. The higher-order tensor renomalization group (HOTRG) method is used to coarse grain the weight tensor in the tensor network representation of the partition function. The renormalized tensor is then used to construct the approximated transfer matrix of an infinite strip of finite width. By diagonalizing the transfer matrix, we obtain the correlation length, magnetization, and energy density, which are used to determine the critical temperature and critical exponents in finite-size scaling analysis. The results show accurate determination of the critical temperature and critical exponents can be achieved.
Article
Materials Science, Multidisciplinary
G. D. A. Wood, D. D. Khalyavin, D. A. Mayoh, J. Bouaziz, A. E. Hall, S. J. R. Holt, F. Orlandi, P. Manuel, S. Bluegel, J. B. Staunton, O. A. Petrenko, M. R. Lees, G. Balakrishnan
Summary: We investigate the magnetic structure of GdRu2Si2 using neutron diffraction and discover higher-order magnetic satellites. We refine a double-Q constant-moment model using powder diffraction and find that the structure contains vortexlike motifs with a one-dimensional topological charge density.
Article
Materials Science, Multidisciplinary
Ashish Kumar Mishra, S. Shanmukharao Samatham, Mark T. F. Telling, A. D. Hillier, Martin R. Lees, K. G. Suresh, V. Ganesan
Summary: We have observed the presence of magnetic rare regions in Fe-doped MnSi that exhibit the quantum Griffiths phase. These rare regions exhibit slow dynamics at low temperatures, resulting in non-Fermi-liquid behavior in heat capacity and magnetization. Our μSR and magnetization measurements indicate that the dynamics freeze into a cluster-glass state below Tf around 1.25 K. These findings are consistent with theoretical models proposed for metallic systems with Heisenberg symmetry and strong disorder exhibiting the quantum Griffiths phase.
Article
Materials Science, Multidisciplinary
Sijie Hao, Wentao Jin, Zbigniew Bukowski, Zhengwang Lin, Yinguo Xiao, Yixi Su
Summary: The magnetic order in Eu(Fe1-xNix)2As2 crystals is studied using polarized neutron diffraction. The Fe and Eu magnetic sublattices are found to be almost decoupled. The Eu sublattice undergoes a dramatic change in its magnetic ground state with Ni doping, transitioning from an A-type antiferromagnetic order to a canted ferromagnetic order. The lack of superconductivity in Eu(Fe1-xNix)2As2 may be attributed to the formation of in-plane ferromagnetism.
Article
Materials Science, Multidisciplinary
Yun-Chung Chen, Yu-Ping Lin, Ying-Jer Kao
Summary: This study presents an example of a new type of insulator that exhibits stable, protected gapless edge states without traditional bulk topological features. The protection of these states arises from mirror antisymmetry, a combination of chiral and mirror symmetries.
Article
Chemistry, Multidisciplinary
Wilgner Lima da Silva, Ashok S. Menon, Martin R. Lees, Reza J. Kashtiban, Marc Walker, Louis F. J. Piper, Emma Kendrick, Richard I. Walton
Summary: A Mn2+-Li-Nb disordered rock-salt oxide cathode is prepared by a solid-state reaction under 5% H-2/N-2 atmosphere, showing a high voltage plateau and irreversible structural changes in the first cycle.
CHEMICAL COMMUNICATIONS
(2023)
Article
Physics, Atomic, Molecular & Chemical
Murari Soundararajan, George R. Bacanu, Francesco Giustiniano, Mark C. Walkey, Gabriela Hoffman, Marina Carravetta, Martin R. Lees, Richard J. Whitby, Malcolm H. Levitt
Summary: This article presents a new variant of the superconducting fulleride Rb3C60, with He-3 atoms encapsulated in the C-60 cages. The characteristics of the superconducting and normal states are examined using He-3 NMR. Evidence is found for the coexistence of vortex liquid and vortex solid phases below the superconducting transition temperature. The spin-lattice relaxation time constant in the superconducting state shows a strong dependence on spectral frequency, which is revealed by two-dimensional NMR using an inverse Laplace transform. Surprisingly, this phenomenon persists, in attenuated form, at temperatures well above the superconducting transition.
APPLIED MAGNETIC RESONANCE
(2023)
