bluuebunny/crossref_metadata_2025_split huggingface dataset:
ERP prototypical matching net: a meta-learning method for zero-calibration RSVP-based image retrieval
Authors: Wei Wei , Qiu Shuang , Zhang Yukun , Mao Jiayu , He Huiguang 
Published: March 2022

Abstract

Objective. A rapid serial visual presentation (RSVP)-based brain-computer interface (BCI) is an efficient information detection technology through detecting event-related potentials (ERPs) evoked by target visual stimuli. The BCI system requires a time-consuming calibration process to build a reliable decoding model for a new user. Therefore, zero-calibration has become an important topic in BCI research. Approach. In this paper, we construct an RSVP dataset that includes 31 subjects, and propose a zero-calibration method based on a metric-based meta-learning: ERP prototypical matching net (EPMN). EPMN learns a metric space where the distance between electroencephalography (EEG) features and ERP prototypes belonging to the same category is smaller than that of different categories. Here, we employ prototype learning to learn a common representation from ERP templates of different subjects as ERP prototypes. Additionally, a metric-learning loss function is proposed for maximizing the distance between different classes of EEG and ERP prototypes and minimizing the distance between the same classes of EEG and ERP prototypes in the metric space. Main results. The experimental results showed that EPMN achieved a balanced-accuracy of 86.34% and outperformed the comparable methods. Significance. Our EPMN can realize zero-calibration for an RSVP-based BCI system.
63,65Cu, 139La-NMR study of Electron-doped High Temperature Cuprate Superconductor T’-La1.8Eu0.2CuO4–y
F
y
Authors: Fukazawa Hideto , Lee Yongsun , Watai Masaki , Tamura Koma , Ohama Tetsuo , Kohori Yoh , Sunohara Toshiki , Shiosaka Kota , Nagaoka Ryoji , Kawamata Takayuki , Koike Yoji 
Published: March 2022

Abstract
T’-La1.8Eu0.2CuO4–y
F
y
(0 ≤ y ≥ 0.125) was measured by 63,6BCu and 139La NMR. This material is an electron-doped high-Tc cuprate superconductor which has Nd2CuO4-type structure (so-called T’-structure). The nuclear spin-lattice relaxation rate 1/T
1 revealed that pseudogap behavior exists in the lightly electron-doped region of y ≤ 0.075 and electron doping suppresses the antiferromagnetic spin flutuations. These behaviors in electron-doped high-T
c cuprate superconductor are analogous with the optimum- and over-doped region in hole-doped type. 139 La NMR spectra shows almost no antiferromagnetic region in the samples of T’-La1.8Eu0.2CuO4–y
F
y
.
Doping induced band renormalization in 122-type Fe-based superconductor
Authors: Pandeya Ram Prakash , Datta Sawani , Sakhya Anup Pradhan , Saha Tanusree , Ninno Giovanni De , Mondal Rajib , Moras Paolo , Jugovac Matteo , Carbone Carlo , Thamizhavel A , Maiti Kalobaran 
Published: March 2022

Abstract
We study the electronic structure of a superconducting composition of 122-type Fe-based pnictide material, CaFe1.9Co0.1As2 employing high resolution angle resolved photoemission spectroscopy technique. The experimental results exhibit three bands close to Fermi level at Γ-point of the Brillouin zone among which only one band crosses the Fermi level. In the parent compound, CaFe2As2, all the three bands cross the Fermi level and form three hole pockets. While the destruction of Fermi pockets due to electron doping (Co-substitution dopes electrons into the system) is expected, we observe significant orbital selective band renormalization with respect to the parent compound. It appears that the effect of spin-orbit coupling is stronger in the doped compound.
Phase diagram of the three-orbital Hubbard-Holstein model simulating Superconducting Tungsten Bronze AxWO3
Authors: Sekikawa Takuya , Ōno Yoshiaki 
Published: March 2022

Abstract
The superconductivity in tungsten bronze Ax
WO3 (A═alkali metal) is studied based on first-principles calculations and orbital fluctuation theory. We discuss the effects of the electron-Jahn-Teller phonon interaction and the on-site Coulomb interaction in the random phase approximation, and obtain a phase diagram on the U — g plane in the low-doped regime at x~0.05, where high-temperature superconductivity has been experimentally observed.
Phase separation in high-Tccuprates
Authors: Moskvin A S , Panov Yu D 
Published: March 2022

AbstractWe develop a minimal non-BCS model for the CuO2planes with the on-site Hilbert space reduced to only three effective valence centers CuO4with different charge, conventional spin, and orbital symmetry, combined in a charge triplet, to describe the low-energy electron structure and the phase states of HTSC cuprates. Using theS= 1 pseudospin algebra we introduce an effective spin-pseudospin Hamiltonian which takes into account local and nonlocal correlations, one- and two-particle transport, and spin exchange. TheT-nphase diagrams of the complete spin-pseudospin model for the CuO2planes were reproduced by means of a site-dependent variational approach within effective field approximation typical for spin-magnetic systems. Limiting ourselves to two-sublattice approximation andnn-couplings we arrived at several Néel-like phases in CuO2planes for parent and doped systems with a single nonzero local order parameter: antiferromagnetic insulator, charge order, gluelessd-wave Bose superfluid phase, and unusual metallic phase. However, the Maxwell’s construction shows the global minimum of free energy is realized for phase separated states which are bounded by the third-order phase transition lineT*(n), which is believed to be responsible for the onset of the pseudogap phenomenon.
Temperature and doping dependence of the singlet and triplet pair susceptibilities in the one-band Hubbard model based on the dynamical mean-field theory
Authors: Inokuma Yusuke , Ōno Yoshiaki 
Published: March 2022

Abstract
The superconductivity in the one-band Hubbard model on a Bethe lattice is investigated on the basis of the dynamical mean-field theory (DMFT) in which the irreducible vertex function has no k-dependence and then only the s-wave superconductivities with the spin-singlet even-frequency and the spin-triplet odd-frequency pairings are possibly realized. We calculate the pair susceptibility by solving the Bethe-Salpeter equation with the use of the linearized DMFT and find that the spin-singlet pair susceptibility is suppressed by the on-site Coulomb interaction U especially for the region near the Mott transition. On the other hand, the spin-triplet pair susceptibility is apparently enhanced by U in the strong correlation regime at very low temperatures where the effective interaction for the triplet pairing is considered to be attractive and then the triplet superconductivity is expected to be realized.
Joint machine learning analysis of muon spectroscopy data from different materials
Authors: Tula T , Möller G , Quintanilla J , Giblin S R , Hillier A D , McCabe E E , Ramos S , Barker D S , Gibson S 
Published: March 2022

Abstract
Machine learning (ML) methods have proved to be a very successful tool in physical sciences, especially when applied to experimental data analysis. Artificial intelligence is particularly good at recognizing patterns in high dimensional data, where it usually outperforms humans. Here we applied a simple ML tool called principal component analysis (PCA) to study data from muon spectroscopy. The measured quantity from this experiment is an asymmetry function, which holds the information about the average intrinsic magnetic field of the sample. A change in the asymmetry function might indicate a phase transition; however, these changes can be very subtle, and existing methods of analyzing the data require knowledge about the specific physics of the material. PCA is an unsupervised ML tool, which means that no assumption about the input data is required, yet we found that it still can be successfully applied to asymmetry curves, and the indications of phase transitions can be recovered. The method was applied to a range of magnetic materials with different underlying physics. We discovered that performing PCA on all those materials simultaneously can have a positive effect on the clarity of phase transition indicators and can also improve the detection of the most important variations of asymmetry functions. For this joint PCA we introduce a simple way to track the contributions from different materials for a more meaningful analysis.
Shear modulus anomaly of multi-conponent superconductor: the case of Mx
Bi2Se3
Authors: How Pye Ton 
Published: March 2022

Abstract
A pair of split superconducting transitions in the presence of a symmetry breaking field is a very definitive signature of multi-component superconductivity[1, 2]. We theoretically study the shear modulus anomaly across such pair of split transitions[3]. The talk will be focused on MxBi2Se3, a nematic superconductor candidate, for which no experimental confirmation of the split transition has been made so far. We propose that the shear modulus C
66 must vanish at the lower transition: a very clear signature detectable by experiments. The observation of shear modulus anomalies would be a conclusive test for the nematic superconductivity hosted by the material.
Superconducting and chiral-glass to insulator transition in phase-glass models in a magnetic field
Authors: Granato Enzo 
Published: March 2022

Abstract
We investigate the quantum phase transitions of a phase-glass model in a magnetic field with frustration parameter f = 1/2, describing the effects random negative Josephson-junction couplings in two-dimensional superconductors. The critical behavior is obtained by a scaling analysis of path-integral Monte Carlo simulations at zero temperature, including corrections to finite-size scaling. A single superconducting and chiral-glass to insulator transition occurs above a disorder threshold with divergent nonlinear magnetic susceptibility, unaffected by the additional magnetic-field frustration. The relevance of this transition for nanohole superconducting thin films doped with magnetic impurities is discussed.
Stability of ordered and disordered phases in the Heisenberg-Kitaev model in a magnetic field
Authors: Cônsoli Pedro M , Andrade Eric C 
Published: March 2022

Abstract
The S = 1/2 Kitaev honeycomb model has attracted significant attention as an exactly solvable example with a quantum spin liquid ground state. In an properly oriented external magnetic field, the system exhibits chiral Majorana edge modes with an associated quantized thermal Hall conductance, and a distinct spin-disordered phase emerges at intermediate field strengths, below the polarized phase. However, since material realizations of Kitaev magnetism invariably display competing exchange interactions, the stability of these exotic phases with respect to additional couplings is a key issue. Here, we report a 24-site exact diagonalization study of the Heisenberg-Kitaev model in a magnetic field applied in the [001] and [111] directions. By mapping the full phase diagram of the model and contrasting the results to recent nonlinear spin-wave calculations, we show that both methods agree well, thus establishing that quantum corrections substantially modify the classical phase diagram. Furthermore, we find that, in a [111] field, the intermediate-field spin-disordered phase is remarkably stable to Heisenberg interactions and may potentially end in a novel quantum tricritical point.
Impurity-Robust Bulk Gapless Excitation in the Yb-Based Zigzag Chain Compound YbCuS2
Authors: Hori Fumiya , Kinjo Katsuki , Kitagawa Shunksaku , Ishida Kenji , Ohmagari Yudai , Onimaru Takahiro 
Published: March 2022

Abstract
We have performed 63Cu-nuclear quadrupole resonance (NQR) measurements using a lump sample of the Yb zigzag-chain compound YbCuS2 with a small surface area to investigate the sample dependence of low-temperature magnetic properties in YbCuS2 by comparing with the previous study with different powdered sample. The line width of NQR signals in the present lump sample is larger than that in the previous powdered sample. In addition, the transition temperature T
N ∼ 0.92 K in the present lump sample is lower than that in the previous powdered sample (∼ 0.95 K). These results suggest that the quality of the present lump sample is worse than that of the previous powdered sample. However, the T-linear behavior of the nuclear spin-lattice relaxation rate 1/T1 was observed below 0.5 K and the value of 1/T
1
T in both samples is almost the same even though the sample quality and sample geometry are different. This suggests that T-linear behavior in 1/T
1 arises from the impurity-robust bulk gapless excitation inherent in YbCuS2 rather than from sample issues such as the sample quality or geometry.
Discord effects of inter-cluster interactions on a cluster-based Haldane state in a triangular spin tube
Authors: Sugimoto Takanori , Tohyama Takami 
Published: March 2022

Abstract
We have recently proposed a new concept of cluster-based Haldane states supported by an inherent chirality in a triangular spin tube with equivalent inter-cluster interactions. In this state, there appear spin-1/2 degrees of freedom consisting of a real spin and a scalar chirality as edge states. With applying a magnetic field, we can observe approximately a half of magnetization of S = 1/2 spin, i.e., a quarter spin magnetization, due to symmetrization of the real spin and the chirality. Here, we consider effects of discord between two types of inter-cluster interactions, inducing anisotropic biquadratic interactions of effective S = 1 spins. The discord brings the edge magnetization nearer to an exact value of quarter spin magnetization, whereas localization of the edge states becomes worse. These effects are also confirmed in a corresponding spin-1 model.
Correlations among Tc, A, and Γ
ο within FL region of T-p phase diagram of heavy-Fermion superconductors
Authors: ElMassalami M. , Castro P. B. , Silva Neto M.B. 
Published: March 2022

Abstract
Extensively reported experimental observations indicate that on varying a control parameter, such as pressure p, within the phase diagram of most quantum critical heavy fermion HF superconductors, one identifies a cascade of distinct electronic states which may be magnetic, of Kondo-type, non-conventional superconducting, Fermi Liquid, FL, or non-FL character. Of particular interest is the part of the phase diagram wherein superconductivity emerges from a strongly renormalized FL state. This region resembles the overdoped region of the T-doping phase diagram of cuprate superconductors. Remarkably, within this highly nontrivial region, one identifies a universal correlation among Tc and

A:
In

T
c

θ

∝

A

−

1
2

(θ is a characteristic energy scale and A is the coefficient of T
2 resistivity term). Commonly, these features are considered to be driven by a Spin-Fluctuation-mediated electron-electron scattering channel. On adopting such a channel and applying standard theories of Migdal-Eliashberg (superconductivity) and Boltzmann (transport), we derive analytic expressions that satisfactorily reproduce the aforementioned empirical correlations.
High-field magnetization and magnetoresistance of the honeycomb Kondo lattice alloys Ce(Pt1-x
Pd
x
)6Al3
Authors: Oishi R. , Miyake A. , Tokunaga M. , Shimura Y. , Umeo K. , Onimaru T. , Takabatake T. 
Published: March 2022

Abstract
CePt6Al3 is a rare example of the Ce-based honeycomb lattice compound. Substitution of the isovalent Pt for Pd transforms the ground state from a paramagnetic heavy-fermion state to an antiferromagnetic (AFM) ordered state. To gain insight into the role of magnetic frustration in the honeycomb Kondo lattice, we have measured the magnetization M(B) and electrical resistivity ρ(B) of Ce(Pt1-x
Pd
x
)6Al3 (x ≤ 0.3) in pulsed magnetic fields up to 60 T. For the single crystal with x = 0, M(B) for B along the easy c axis exhibits a metamagnetic increase and ρ(B || c) bends at Bm = 28 T. Taking the temperature at a shoulder in the magnetic susceptibility χ
(ल) for B ‖ c as T

χm = 17 K, the ratio
μB
B
m/K
B
T

>χm is estimated to be 1.1. This value agrees with those reported for Ce-based paramagnetic heavy-fermion compounds with similar magnitudes of B
m. With increasing x from 0 to 0.3 in polycrystalline samples, the magnitude of M(B = 60 T) at 1.4 K increases from 0.75 to 2.0
μβ/Ce, indicating the recovery of localized 4f moments by the Pd substitution for Pt. Using the data of M(B) and ρ(B) for x = 0.1, 0.2, 0.3, we constructed B-T phase diagrams, which show a trend from a small moment AFM ordered state for x = 0.1 to a large moment AFM ordered state for x = 0.3.
Low-temperature physical properties of a new cubic compound CeMgZn2
Authors: Matsuoka E , Yoshimoto T , Sugawara H , Sakurai T , Ohta H 
Published: March 2022

Abstract
Magnetic and transport properties of a new cubic compound CeMgZn2 have been examined by measuring the magnetic susceptibility, the magnetization, the electrical resistivity, and the specific heat. CeMgZn2 is a Kondo-lattice compound with trivalent Ce ions. The magnetic susceptibility measured at 0.1 T exhibits a shoulder and a cusp at T
N1 = 5.4 K and T
N2 = 3.1 K, respectively. T
N1 and T
N2 correspond to the antiferromagnetic-transition temperatures since these temperatures decrease with increasing magnetic field. The large value of the paramagnetic Curie temperature divided by T
N1 (13.5) implies that T
N1 is suppressed by geometrical frustration on a face-centered cubic Ce sublattice. The geometrical frustration may also be responsible for the appearance of many magnetic phases in magnetic fields.
Low-temperature physical properties of a new orthorhombic compound Ce2Ir3Sb4
Authors: Komoda T , Matsuoka E , Sugawara H , Sakurai T , Ohta H 
Published: March 2022

Abstract
We have synthesized polycrystalline samples of a new orthorhombic compound Ce2lr3Sb4 and investigated their physical properties by measuring the magnetization, the electrical resistivity, and the specific heat down to 0.4 K. From the results of electrical resistivity measurements, it was found that Ce2Ir3Sb4 is a Kondo lattice compound. We found that Ce2Ir3Sb4 does not show any phase transition down to 0.4 K. The specific heat peak at 1.3 K is not due to a phase transition but due to the Schottky specific heat caused by the crystalline electric field splitting of the 4f level of Ce ions.
Possible routes for the synthesis of nanowires of intermetallic compounds: The case of CeIn3
Authors: Carvalho M. H. , Freitas G. S. , Souza J. C. , Campanelli R. B. , Pizzi H. B. , Mercena S. G. , Puydinger dos Santos M.V. , Béron F. , Rosa P. F. S. , Pirota K.R. , Pagliuso P. G. 
Published: March 2022

Abstract
In this work, we investigated the role of different parameters in the synthesis of intermetallic nanowires of CeIn3 by the metallic-flux nanonucleation (MFNN) method such as template pore diameter, crystallization temperature, heat treatment temperature, and synthesis time. Depending on the growing parameters, we obtained CeIn3 nanowires (d ∼ 350 nm) or CeAlO3 nanotubes. For the nanowires, we observed a suppression of the CeIn3 antiferromagnetic transition from the bulk TN ∼ 10 K to the nanowire system TN ∼ 3 K, which may be associated with the dimensionality affecting the interplay between magnetic exchange interactions, crystalline electrical field, and Kondo effects. We assume that the CeAlO3 nanotubes may result from a reaction with the alumina template and consequent rare-earth oxidation. Our work shows that even it is a great challenge to find the correct growth path of a particular intermetallic compound, the MFNN method can be a promising route to obtain rare-earth based nanowires.
Effect of 3p- and 5d-electron doping on the Kondo Semiconductor CeFe2Al10
Authors: Tripathi Rajesh , Adroja D T , Lees M R , Anand V K , Sundaresan A , Langridge S , Bhattacharyya A , Muro Y , Hayashi K , Takabatake T 
Published: March 2022

Abstract
We examined the effect of 3p- and 5d-electron doping on the Kondo semiconductor CeFe2Al10 by means of the electrical resistivity (ρ), magnetic susceptibility (χ), and specific heat (C) measurements. The results show that in the 3p-electron-doped system CeFe2Al10−y
Si
y
, the semiconducting behavior is suppressed for y = 0.05, and the system adopts a metallic ground state with an increase in the density of states at the Fermi level. The Si substitution leads to a large decrease in the paramagnetic Weiss temperature θP
indicating a reduction in c-f hybridization strength, however the Si does not induce magnetic order up to y = 0.3 down to 2K. The systematic changes in ρ(T), χ(T), and C(T) are similar to those for 5d-electron doped system CeFe2−x
Ir
x
Al10, although, Ir substitution induces a bulk antiferromagnetic transition below 3.1 K in CeFe1.7Ir0.3Al10. These changes can be explained by the collapse of the hybridization gap due to the suppression of the c-f hybridization effect. Our results further confirm that the collapse of the spin/charge gap by an excess electron doping is one of the universal features of the Kondo semiconductors CeT
2Al10 (T = Fe, Ru, and Os).
Electronic structure of a Kondo lattice system CeCuAs2
Authors: Datta Sawani , Pandeya Ram Prakash , Dey Arka Bikash , Schlueter Christoph , Gloskovskii Andrei , Peixoto Thiago , Thamizhavel Arumugam , Maiti Kalobaran 
Published: March 2022

Abstract
We study the electronic properties of a Ce-based Kondo material, CeCuAs2 employing high-resolution hard x-ray photoemission spectroscopy. The measurements were done with different photon energies to probe the surface-bulk differences of the electronic structure. Experimental results show significant difference in the hybridization physics for the surface and bulk electronic structures indicating different Ce valency at the surface compared to the bulk. Surface termination appears to play an important role in the correlation physics of this system. In addition, the experimental spectra show loss features due to plasmon excitations. These results bring out complexity of this novel Kondo lattice system that does not show magnetic order down to the lowest temperature studied and have significantly different surface-bulk properties.
Inelastic neutron scattering study of crystalline electric field excitations in a cubic compound PrMgNi4
Authors: Kusanose Y. , Onimaru T. , Yamane Y. , Umeo K. , Takabatake T. , Guidi T. , Le D. , Adroja D.T. 
Published: March 2022

Abstract
We performed inelastic neutron scattering experiments on PrMgNi4 with the cubic MgSnCu4-type structure. The magnetic excitations were observed at 1.1, 2.5, 5.9, 10.7, and 11.7 meV. Since the energy of the excitations is constant for |
Q
| < 5 Å−1, they are ascribed to the crystalline electric field (CEF) excitations of the Pr3+ ions. We adopted CEF parameters of W = −3.3 K and x = 0.8 for the cubic T
d point group to reproduce the strong excitations at 1.1, 10.7, and 11.7 meV. The calculated CEF level scheme reveals the Γ3 doublet ground state with the quadrupolar degrees of freedom and the excited states of Γ4 triplet (1.4 meV), Γ1 singlet (3.4 meV), and Γ5 triplet (13.5 meV). This scheme, however, does not explain the observed two excitations at 2.5 and 5.9 meV. These additional excitations may arise from splitting of the doublet by symmetry lowering due to excess Mg atoms occupying the Pr sites. This splitting is probably responsible for the absence of the long-range quadrupole order in PrMgNi4.
Magnetic structure of an antiferromagnet NdRh2Zn20 investigated by powder neutron diffraction
Authors: Yamamoto R. , Shimura Y. , Umeo K. , Takabatake T. , Damay F. , Mignot J.-M. , Onimaru T. 
Published: March 2022

Abstract
Powder neutron diffraction measurements were carried out to investigate the magnetic structure of the antiferromagnet NdRh2Zn20. The magnetic reflections observed for T ≤ 1.0 K are indexed by the propagation vector of k = (1/2, 1/2, 1/2). From the analysis of the intensity of magnetic reflections, a magnetic structure described by the Γ6 representation is proposed. The magnetic moments are parallel to the

[
11

2
¯

]

or

[

1
¯

10
]

direction and stacked with a sequence of up-up-down-down along the [111] direction.