Gendo Oomi

Kyushu University

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Tomoko Kagayama

Osaka University

Masashi Ohashi

Kanazawa University

Yoshiya Uwatoko

The University of Tokyo

Takemi Komatsubara

Tohoku University

Fuminori Honda

Tohoku University

Nobuo Môri

The University of Tokyo

YŌ

Yoshichika Ōnuki

Tokyo Metropolitan University

Kōki Takanashi

Tohoku University

T. Nakano

Niigata University

Kesami Saito

Tohoku University

Cooperative Institutions

Tohoku University

The University of Tokyo

Kyushu University

Osaka University

University of Tsukuba

Hokkaido University

Kumamoto University

Institute for Materials Research, Tohoku University

Japan Science and Technology Agency

National Institute of Advanced Industrial Science and Technology

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Simple Experimental Procedure under Quasi-Hydrostatic Pressure up to 15 GPa at Low Temperature

Japanese Journal of Applied Physics (2009)

Masashi Ohashi Gendo Oomi

We have demonstrated the precise measurement of electrical resistance under high pressure at low temperature. By using Bridgman anvils made of tungsten carbide, quasi-hydrostatic pressure is generated up to ∼15 GPa in the working space, which is one order of magnitude larger than that of a typical diamond anvil cell. The application of this technique is demonstrated by the measurement of the electrical resistivity of chromium and the effect of pressure on the superconducting temperature of lead.

Hydrostatic pressure

Diamond anvil cell

Tungsten Carbide

Hydrostatic equilibrium

10.1143/jjap.48.070221

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Citations (9)

Pressure-enhanced giant magnetoresistance in Fe/Cr magnetic multilayers

Journal of the Korean Physical Society (2013)

Gendo Oomi Shuhei Higashihara Kazufumi Suenaga Kesami Saito Kōki Takanashi

Ambient pressure

10.3938/jkps.62.1929

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Citations (1)

High Pressure X-Ray Study of Anomalous Bulk Modulus of an Fe₇₀Ni₃₀ Invar Alloy

Journal of the Physical Society of Japan (1981)

Gendo Oomi Nobuo Môri

Pressure dependence of the lattice constant is measured for the pressure-stabilized fcc phase of an Fe 70 Ni 30 Invar alloy by high pressure X-ray diffraction method at 77.4 K. The bulk modulus B in the ferromagnetic phase is obtained to be (14 ±1) ×10 2 kbar. A discontinuous increase in B , Δ B , is found to be Δ B ≈700 kbar near 64 kbar. The magnitude Δ B at 77.4 K is the same as that observed at the ferromagnetic to paramagnetic phase transition at room temperature around 15 kbar.

Invar

Lattice constant

Lattice (music)

10.1143/jpsj.50.1043

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Citations (8)

Thermal expansion of single crystalline CeInCu2

Physica B Condensed Matter (1990)

Gendo Oomi Tomoko Kagayama Yoshichika Ōnuki Takemi Komatsubara

10.1016/0921-4526(90)90268-y

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Citations (25)

The effect of pressure on the superconductivity and magnetism of RuSr2GdCu2O8

Journal of Physics Condensed Matter (2002)

Gendo Oomi Fuminori Honda T. Eto D P Hai Shiho Kamizawa

A new hybrid ruthenate-cuprate superconductor RuSr 2 GdCu 2 O 5 has been synthesized. This compound exhibits superconductivity and magnetic ordering around 40 K (=T c ) and 130 K (=T m ). The effect of pressure on the electrical resistance has been measured up to 2.1 GPa in order to make clear the interplay between the magnetism and the superconductivity. It is found that both T c and T m increase with pressure with rates of dT c /dP = 1.9 K GPa -1 and dT m /dP = 5.7 K GPa -1 , which indicates that the superconductivity does not compete with the magnetic ordering. An x-ray diffraction experiment under pressures up to 13 GPa has been carried out in order to clarify the relation between the electronic properties and the lattice compression.

Magnetism

10.1088/0953-8984/14/44/370

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Citations (2)

Effect of pressure on the anomalous magnetoresistance and antiferromagnetism of single crystal GdB₄

Journal of Physics Conference Series (2009)

Gendo Oomi Masashi Ohashi Beongki Cho

Electrical resistance of single-crystalline GdB4 has been measured at high pressures and high magnetic fields. The antiferromagnetic ordering temperature TN increases with pressure at a rate 0.3 K/GPa, but the hidden transition temperature Ta is almost pressure independent. The magnitude of magnetoresistance at 4.2 K (about 6000% at 8.5 T) is not affected by applying pressures below 3 GPa. This fact suggests similar origins of the hidden transition and of the extremely large magnetoresistance.

10.1088/1742-6596/176/1/012038

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Citations (7)

Precursor phenomena to pressure- induced superconductivity in the thermal expansion of UGe₂

Journal of Nuclear Science and Technology (2002)

Gendo Oomi Masashi Ohashi K. Nishimura Yoshichika Ōnuki

Thermal expansions of single crystalline UGe2 have been measured at high pressure up to 2 GPa. It is found at ambient pressure that there is a large anisotropy in the α(T) curve depending on the ciystal axis and discontinuous change corresponding to ferromagnetic ordering near 50 K(= TC). Furthermore a small change in α (T) is observed near 25 K (= T*) below TC, which may be related with a phase transition. We studied the pressure dependence of TC and T*, which are strongly dependent on pressure and diappear near 1.8 GPa and 1.2 GPa, respectively. Anomalous pressure dependence is also found in the α (T) and ρ(T) still above TC. The origin of these anomalies will be discussed briefly in connection with the ferromagnetism and pressure-induced superconductivity.

Ambient pressure

Transition temperature

Superconducting transition temperature

10.1080/00223131.2002.10875415

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Citations (6)

27a-YF-2 Thermal expansion and magnetostriction of heavy fermion compounds at ambient and high pressure

Abstracts of the meeting of the Physical Society of Japan. Sectional meeting (1995)

Gendo Oomi Tomoko Kagayama

Ambient pressure

Source

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Citations (0)

Magnetic Phase Diagram of Ce₁₋_xEr_xAl₂ Intermetallic Compounds

Proceedings of the International Conference on Strongly Correlated Electron Systems (SCES2019) (2014)

Masashi Ohashi H. Miyagawa Gendo Oomi T. Nakano Isamu Satoh

10.7566/jpscp.3.011083

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Citations (2)

Electrical Resistivity of Amorphous Ce–Ru Alloy under High Pressure and High Magnetic Field

Journal of the Physical Society of Japan (1996)

Takeshi Sakai Tomoko Kagayama Gendo Oomi K. Sumiyama Yoshiya Homma

The electrical resistivity, ρ, of amorphous Ce 58 Ru 42 alloy (a-CeRu) has been measured as a function of temperature ( T ) at various pressures ( P ) up to 14 GPa. At room temperature ρ decreases rapidly with increasing pressure: ∂log ρ/∂ P =-0.9 GPa -1 below 2 GPa. The log T dependence in the ρ( T ) curve due to Kondo scattering is observed up to 14 GPa. The slope of the ρ vs log T curve decreases with increasing pressure. At 4.2 K the magnetoresistance, Δρ/ρ, is positive and decreases with increasing pressure. These results suggest that the Kondo temperature, T K , decreases with pressure in a-CeRu, i.e., the Kondo effect is suppressed by applying pressure.

10.1143/jpsj.65.1154

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Citations (4)