Araki, Yasufumi; Suenaga, Daiki*; Suzuki, Kei; Yasui, Shigehiro*
Physical Review Research (Internet), 3(2), p.023098_1 - 023098_17, 2021/05
Spins of relativistic fermions are related to their orbital degrees of freedom. In order to quantify the effect of hybridization between relativistic and nonrelativistic degrees of freedom on spin-orbit coupling, we focus on the spin-orbital (SO) crossed susceptibility arising from spin-orbit coupling. The SO crossed susceptibility is defined as the response function of their spin polarization to the ``orbital'' magnetic field, namely the effect of magnetic field on the orbital motion of particles as the vector potential. Once relativistic and nonrelativistic fermions are hybridized, their SO crossed susceptibility gets modified at the Fermi energy around the band hybridization point, leading to spin polarization of nonrelativistic fermions as well. These effects are enhanced under a dynamical magnetic field that violates thermal equilibrium, arising from the interband process permitted by the band hybridization. Its experimental realization is discussed for Dirac electrons in solids with slight breaking of crystalline symmetry or doping, and also for quark matter including dilute heavy quarks strongly hybridized with light quarks, arising in a relativistic heavy-ion collision process.
Shitade, Atsuo*; Araki, Yasufumi
Physical Review B, 103(15), p.155202_1 - 155202_8, 2021/04
The axial magnetic effect (AME) is one of the anomalous transport phenomena in which the energy current is induced by an axial magnetic field. Here we numerically study the AME for the relativistic Wilson fermion in the axial magnetic field and a twisted Dirac semimetal. The AME current density inside the bulk is nonzero, and particularly in the low energy regime for the former model, it is explained by the field-theoretical results without any fitting parameter. However, for both models, the average AME current density vanishes owing to the surface contribution. The axial gauge field is regarded as the spatially modulated (effective) Zeeman field and induces the spatially modulated energy magnetization. The AME is attributed to the magnetization energy current and hence cannot be observed in transport experiments.
Kim, J.-Y.*; Kim, H.-C.*; Yang, G.-S.*; Oka, Makoto
Physical Review D, 103(7), p.074025_1 - 074025_21, 2021/04
We investigate the electromagnetic transitions of the singly charmed baryons with spin 3/2, based on a pion mean-field approach, also known as the chiral quark-soliton model, taking into account the rotational corrections and the effects of flavor SU(3) symmetry breaking. We examine the valence- and sea-quark contributions to the electromagnetic transition form factors and find that the quadrupole form factors of the sea-quark contributions dominate over those of the valence-quark ones in the smaller region, whereas the sea quarks only provide marginal contributions to the magnetic dipole transition form factors of the baryon sextet with spin 3/2.The effects of the flavor SU(3) symmetry breaking are in general very small except for the forbidden transition by -spin symmetry. We also discuss the widths of the radiative decays for the baryon sextet with spin 3/2, comparing the present results with those from other works.
Bersweiler, M.*; Sinaga, E. P.*; Peral, I.*; Adachi, Nozomu*; Bender, P.*; Steinke, N.-J.*; Gilbert, E. P.*; Todaka, Yoshikazu*; Michels, A.*; Oba, Yojiro
Physical Review Materials (Internet), 5(4), p.044409_1 - 044409_7, 2021/04
Ieda, Junichi; Yamane, Yuta*
Physical Review B, 103(10), p.L100402_1 - L100402_5, 2021/03
Shick, A. B.*; Fujimori, Shinichi; Pickett, W. E.*
Physical Review B, 103(12), p.125136_1 - 125136_12, 2021/03
Miao, P.*; Tan, Z.*; Lee, S. H.*; Ishikawa, Yoshihisa*; Torii, Shuki*; Yonemura, Masao*; Koda, Akihiro*; Komatsu, Kazuki*; Machida, Shinichi*; Sano, Asami; et al.
Physical Review B, 103(9), p.094302_1 - 094302_18, 2021/03
The layered perovskite PrBaCoO demonstrates a strong negative thermal expansion (NTE) which holds potential for being fabricated into composites with zero thermal expansion. The NTE was found to be intimately associated with the spontaneous magnetic ordering, known as magneto-volume effect (MVE). Here we report with compelling evidences that the continuous-like MVE in PrBaCoO is intrinsically of discontinuous character, originating from an magnetoelectric transition from an antiferromagnetic insulating large-volume (AFILV) phase to a ferromagnetic less-insulating small-volume (FLISV) phase. Furthermore, the magnetoelectric effect (ME) shows high sensitivity to multiple external stimuli such as temperature, carrier doping, hydrostatic pressure, magnetic field etc. In contrast to the well-known ME such as colossal magnetoresistance and multi-ferroic effect which involve symmetry breaking of crystal structure, the ME in the cobaltite is purely isostructural. Our discovery provides a new path way to realizing the ME as well as the NTE, which may find applications in new techniques.
Go, Shintaro*; Ideguchi, Eiji*; Yokoyama, Rin*; Aoi, Nori*; Azaiez, F.*; Furutaka, Kazuyoshi; Hatsukawa, Yuichi; Kimura, Atsushi; Kisamori, Keiichi*; Kobayashi, Motoki*; et al.
Physical Review C, 103(3), p.034327_1 - 034327_8, 2021/03
Taniguchi, Yasutaka*; Yoshida, Kazuki; Chiba, Yohei*; Kanada-En'yo, Yoshiko*; Kimura, Masaaki*; Ogata, Kazuyuki*
Physical Review C, 103(3), p.L031305_1 - L031305_5, 2021/03
Based on the Ti(,)Ca reaction analysis, this study reports that -particle formation in the medium-mass Ti nucleus is pronounced more compared to that expected through mean-field approximations. Moreover, the estimated average distance between the particle and residue equals approximately 4.5 fm. This result poses a challenge to describe the four nucleon correlations using microscopic nuclear models.
Suenaga, Daiki*; Araki, Yasufumi; Suzuki, Kei; Yasui, Shigehiro*
Physical Review D, 103(5), p.054041_1 - 054041_17, 2021/03
We investigate the influence of the Kondo effect, namely, the nonperturbative effect induced by heavy impurities, on the chiral separation effect (CSE) in quark matter. We employ a simple effective model incorporating the Kondo condensate made of a light quark and a heavy quark, and compute the response function of the axial current to the magnetic field in the static and dynamical limits. As a result, we find that the Kondo effect catalyzes the CSE in both of the limits, and in particular the CSE in the dynamical limit can be enhanced by a factor of approximately 3. Our findings clearly show that the presence of heavy impurities in quark matter can play an important role in the transport phenomena of light quarks induced by a magnetic field.
Sato, Yoshiki*; Honda, Fuminori*; Maurya, A.*; Shimizu, Yusei*; Nakamura, Ai*; Homma, Yoshiya*; Li, D.*; Haga, Yoshinori; Aoki, Dai*
Physical Review Materials (Internet), 5(3), p.034411_1 - 034411_9, 2021/03
Araki, Yasufumi; Suenaga, Daiki*; Suzuki, Kei; Yasui, Shigehiro*
Physical Review Research (Internet), 3(1), p.013233_1 - 013233_12, 2021/03
We investigate two different types of relativistic Kondo effects, distinguished by heavy-impurity degrees of freedom, by focusing on the energy-momentum dispersion relations of the ground state with condensates composed of a light Dirac fermion and a nonrelativistic impurity fermion. Heavy fermion degrees of freedom are introduced in terms of two types of heavy-fermion effective theories, in other words, two heavy-fermion limits for the heavy Dirac fermion, which is known as the heavy-quark effective theories (HQETs) in high-energy physics. While the first one includes only the heavy-particle component, the second one contains both the heavy-particle and heavy-antiparticle components, which are opposite in their parity. From these theories, we obtain two types of Kondo effects, in which the dispersions near the Fermi surface are very similar, but they differ in the structure at low momentum. We also classify the possible forms of condensates in the two limits. The two Kondo effects will be examined by experiments with Dirac/Weyl semimetals or quark matter, lattice simulations, and cold-atom simulations.
Physical Review B, 103(8), p.085118_1 - 085118_7, 2021/02
Shizuma, Toshiyuki*; Minato, Futoshi; Omer, M.*; Hayakawa, Takehito*; Ogaki, Hideaki*; Miyamoto, Shuji*
Physical Review C, 103(2), p.024309_1 - 024309_8, 2021/02
Low-lying dipole transitions in Pb were measured via nuclear photon scattering using a quasi-monochromatic, linearly polarized photon beam. The electric () and magnetic () dipole strengths were extracted for excitation energies up to 6.8 MeV. The present (,) results, combined with (,) data from the literature, were used to investigate the and photoabsorption cross sections near the neutron separation energy by comparison with predictions of the particle-vibration coupling on top of the quasi-particle random phase approximation (PVC+QRPA).
Chazono, Yoshiki*; Yoshida, Kenichi*; Yoshida, Kazuki; Ogata, Kazuyuki*
Physical Review C, 103(2), p.024609_1 - 024609_7, 2021/02
The isoscalar pair is expected to emerge in nuclei. We aim to clarify the correspondence between the pairing strength in many-body calculation and the cross section of proton-induced deuteron knockout (, ) reaction on O. The radial wave function of the isoscalar pair with respect to the center of O is calculated with the energy density functional (EDF) approach and is implemented in the distorted wave impulse approximation framework. The pairing strength in the EDF calculation is varied and the corresponding change in the cross section is investigated. A clear dependence of the cross section is found. The nuclear distortion is found to make the dependence stronger. Because of the clear -coross section correspondence, the (, ) reaction will be a promising probe for the isoscalar pair in nuclei. For quantitative discussion, further modification of the description of the reaction process will be necessary.
Yang, Z. H.*; Kubota, Yuki*; Corsi, A.*; Yoshida, Kazuki; Sun, X.-X.*; Li, J. G.*; Kimura, Masaaki*; Michel, N.*; Ogata, Kazuyuki*; Yuan, C. X.*; et al.
Physical Review Letters, 126(8), p.082501_1 - 082501_8, 2021/02
A quasifree (,) experiment was performed to study the structure of the Borromean nucleus B, which had long been considered to have a neutron halo. By analyzing the momentum distributions and exclusive cross sections, we obtained the spectroscopic factors for and orbitals, and a surprisingly small percentage of 9(2)% was determined for . Our finding of such a small component and the halo features reported in prior experiments can be explained by the deformed relativistic Hartree-Bogoliubov theory in continuum, revealing a definite but not dominant neutron halo in B. The present work gives the smallest - or -orbital component among known nuclei exhibiting halo features and implies that the dominant occupation of or orbitals is not a prerequisite for the occurrence of a neutron halo.
Shamoto, Shinichi; Yamauchi, Hiroki; Ikeuchi, Kazuhiko*; Kajimoto, Ryoichi; Ieda, Junichi
Physical Review Research (Internet), 3(1), p.013169_1 - 013169_9, 2021/02
Shinaoka, Hiroshi*; Nagai, Yuki
Physical Review B, 103(4), p.045120_1 - 045120_8, 2021/01
no abstracts in English
Iwasa, Naohito*; Ishikawa, Shunki*; Kubono, Shigeru*; Sakakibara, T.*; Kominato, Kazuya*; Nishio, Katsuhisa; Matsuda, Makoto; Hirose, Kentaro; Makii, Hiroyuki; Orlandi, R.; et al.
Physical Review C, 103(1), p.015801_1 - 015801_5, 2021/01
Shimizu, Noritaka*; Tsunoda, Yusuke*; Utsuno, Yutaka; Otsuka, Takaharu*
Physical Review C, 103(1), p.014312_1 - 014312_11, 2021/01
no abstracts in English