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Hisatomo Harima

Bio: Hisatomo Harima is an academic researcher from Kobe University. The author has contributed to research in topics: Fermi surface & De Haas–van Alphen effect. The author has an hindex of 43, co-authored 481 publications receiving 8577 citations. Previous affiliations of Hisatomo Harima include Los Alamos National Laboratory & Osaka Prefecture University.


Papers
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TL;DR: In this paper, the de Haas-van Alphen (dHvA) experiment was carried out for an antiferromagnet CeRhIn 5 at high pressures up to 3 GPa.
Abstract: We carried out the de Haas–van Alphen (dHvA) experiment for an antiferromagnet CeRhIn 5 at high pressures up to 3 GPa. The cross-sectional areas of the Fermi surfaces due to main dHvA branches α i and β 2 at ambient pressure, which are well explained by two kinds of nearly cylindrical Fermi surfaces of a non-4 f reference compound LaRhIn 5 , are unchanged up to about 2.3 GPa, while the corresponding cyclotron masses m c * increase steeply above a pressure P * = 1.6 GPa where pressure-induced superconductivity sets in : m * c = 5.5 m 0 at ambient pressure, 20 m 0 at 1.6 GPa and 60 m 0 at 2.2 GPa for branch β 2 , for example. Above 2.4 GPa, new dHvA branches appear, which are in good agreement with the corresponding dHvA branches of a 4 f -itinerant heavy fermion superconductor CeCoIn 5 , indicating that the 4 f electron of CeRhIn 5 becomes itinerant and significantly contributes to the volume of the Fermi surface. The 4 f -electron character is thus changed from localized to itinerant at a critical pressur...

353 citations

Journal ArticleDOI
TL;DR: In this paper, the surface properties of LaRhIn 5 and CeTIn 5 (T: Co, Rh and Ir) were studied via the de Haas-van Alphen (dHvA) experiment.
Abstract: We have studied Fermi surface properties of LaRhIn 5 and CeTIn 5 (T: Co, Rh and Ir) via the de Haas–van Alphen (dHvA) experiment. The Fermi surface of a non-4 f reference compound LaRhIn 5 is quasi...

246 citations

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TL;DR: In this article, the eigenfunctions and eigenvalues of the crystal electric field for 4 f n configurations are labeled by the irreducible representations of the point group T h.
Abstract: Crystal electric fields for the cubic point groups are reexamined and it is found that the new term O 6 2 - O 6 6 is nonvanishing for the cubic point groups T h and T due to the lack of Umklappung and fourfold symmetry axis of the point group O h . The eigenfunctions and eigenvalues of the crystal electric field for 4 f n configurations are labeled by the irreducible representations of the point group T h . The degeneracy of each sublevel does not change as compared with those of the point group O h , but some eigenfunctions and eigenvalues are affected by the new term. Thus inelastic neutron scattering spectra for T and T h are different from those for O h due to different transition probabilities and selection rules.

212 citations

Journal ArticleDOI
TL;DR: In this article, interference of impulsively excited coherent phonons in semimetals has been studied by using a double-pulse pump-probe technique, and the amplitude after the second pulse shows a sinusoidal dependence as a function of the separation time.
Abstract: Interference of impulsively excited coherent phonons in semimetals has been studied by using a double‐pulse pump–probe technique. Enhancement of the oscillation amplitude of an A1g mode is observed when the separation time of the double‐pulse is matched to the period of the phonon oscillation, and a cancellation is observed when the separation time is adjusted to half the period of the phonon oscillation. The amplitude after the second pulse shows a sinusoidal dependence as a function of the separation time, and this dependence is explained in terms of a superposition of two coherent phonon oscillations. In addition, not only the A1g mode but also an Eg mode have been observed by electro‐optic sampling.

187 citations

Journal ArticleDOI
TL;DR: In this article, the de Haas-van Alphen (dHvA) oscillation was observed in both the normal and superconducting mixed states of a heavy-fermion superconductor CeCoIn5.
Abstract: We observed de Haas-van Alphen (dHvA) oscillation in both the normal and superconducting mixed states of a heavy-fermion superconductor CeCoIn5. The Fermi surfaces are found to consist of nearly cylindrical Fermi surfaces and small ellipsoidal ones, reflecting the unique tetragonal crystal structure. The detected cyclotron masses of 5-87 m0 for these Fermi surfaces are extremely large, and correspond to a large electronic specific heat coefficient of about 1000 mJ K-2 mol-1. The cyclotron masses are also found to be field dependent in both the normal and mixed states.

179 citations


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[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

01 Sep 1955
TL;DR: In this paper, the authors restrict their attention to the ferrites and a few other closely related materials, which are more closely related to anti-ferromagnetic substances than they are to ferromagnetics in which the magnetization results from the parallel alignment of all the magnetic moments present.
Abstract: In this chapter, we will restrict our attention to the ferrites and a few other closely related materials. The great interest in ferrites stems from their unique combination of a spontaneous magnetization and a high electrical resistivity. The observed magnetization results from the difference in the magnetizations of two non-equivalent sub-lattices of the magnetic ions in the crystal structure. Materials of this type should strictly be designated as “ferrimagnetic” and in some respects are more closely related to anti-ferromagnetic substances than they are to ferromagnetics in which the magnetization results from the parallel alignment of all the magnetic moments present. We shall not adhere to this special nomenclature except to emphasize effects, which are due to the existence of the sub-lattices.

2,659 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the usefulness of calculated multiplet peaks to fit high-resolution iron 2p3/2 spectra from high-spin compounds. And they found that the multiplets were found to fit most spectra well, particularly when contributions attributed to surface peaks and shake-up satellites were included.
Abstract: Ferrous (Fe2+) and ferric (Fe3+) compounds were investigated by XPS to determine the usefulness of calculated multiplet peaks to fit high-resolution iron 2p3/2 spectra from high-spin compounds. The multiplets were found to fit most spectra well, particularly when contributions attributed to surface peaks and shake-up satellites were included. This information was useful for fitting of the complex Fe 2p3/2 spectra for Fe3O4 where both Fe2+ and Fe3+ species are present. It was found that as the ionic bond character of the iron —ligand bond increased, the binding energy associated with either the ferrous or ferric 2p3/2 photoelectron peak also increased. This was determined to be due to the decrease in shielding of the iron cation by the more increasingly electronegative ligands. It was also observed that the difference in energy between a high-spin iron 2p3/2 peak and its corresponding shake-up satellite peak increased as the electronegativity of the ligand increased. The extrinsic loss spectra for ion oxides are also reported; these are as characteristic of each species as are the photoelectron peaks. Copyright © 2004 John Wiley & Sons, Ltd.

2,637 citations

Journal ArticleDOI
TL;DR: In this paper, the authors describe the state-of-the-art computational methodology for calculating the structure and energetics of point defects and impurities in semiconductors and pay particular attention to computational aspects which are unique to defects or impurities, such as how to deal with charge states and how to describe and interpret transition levels.
Abstract: First-principles calculations have evolved from mere aids in explaining and supporting experiments to powerful tools for predicting new materials and their properties. In the first part of this review we describe the state-of-the-art computational methodology for calculating the structure and energetics of point defects and impurities in semiconductors. We will pay particular attention to computational aspects which are unique to defects or impurities, such as how to deal with charge states and how to describe and interpret transition levels. In the second part of the review we will illustrate these capabilities with examples for defects and impurities in nitride semiconductors. Point defects have traditionally been considered to play a major role in wide-band-gap semiconductors, and first-principles calculations have been particularly helpful in elucidating the issues. Specifically, calculations have shown that the unintentional n-type conductivity that has often been observed in as-grown GaN cannot be a...

2,557 citations