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Spring recreation 2022 @ Arashiyama

Spring recreation 2022 @ Arashiyama

This year’s Spring Rec was held at Arashiyama on May 8th. We gathered at JR Saga-Arashiyama Station and went around in this order: Togetsu Bridge, Arashiyama Monkey Park, and Bamboo Forest Path. We headed to Togetsu Bridge. Fortunately, the weather was very good. Although it was the last day of...
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Novel law of nonlinear optical response in strongly correlated electron systems

Novel law of nonlinear optical response in strongly correlated electron systems

In the Mott insulator Ca2RuO4, which is a strongly correlated material material, we observed for the first time the generation of high-order harmonics that convert a strong infrared laser beam into visible light. Our experiments show that the intensity of the generated signal follows a surprisingly simple rule. In recent years,...
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Observation of Antiferromagnetic Order as Odd-Parity Multipoles inside the Superconducting Phase in CeRh2As2

Observation of Antiferromagnetic Order as Odd-Parity Multipoles inside the Superconducting Phase in CeRh2As2

Spatial inversion symmetry in crystal structures is closely related to the superconducting (SC) and magnetic properties of materials. Recently, several theoretical proposals that predict various interesting phenomena caused by the breaking of the local inversion symmetry have been presented. However, experimental validation has not yet progressed owing to the lack...
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Autumn recreation 2021 @ Toji Temple and Kyoto Aquarium

Autumn recreation 2021 @ Toji Temple and Kyoto Aquarium

This year's Fall Rec was held on November 7th. (The day before, we did some work before the blackout, and the next day, we had the rec. It's nice to be with everyone in the lab all the time!) There were many candidates, including mountain climbing, the zoo, and the...
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Pairing interaction in superconducting UCoGe tunable by magnetic field

Pairing interaction in superconducting UCoGe tunable by magnetic field

The mechanism of unconventional superconductivity, such as high-temperature-cuprate, Fe-based, and heavy-fermion superconductors, has been studied as a central issue in condensed-matter physics. Spin fluctuations, instead of phonons, are considered to be responsible for the formation of Cooper pairs, and many efforts have been made to confirm this mechanism experimentally. Although...
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We are a research group in experimental physics at Kyoto University led by Profs. Yoshi Maeno and Kenji Ishida. Our research focuses on various phenomena in strongly correlated materials where strong electron–electron interactions lead to emerging physical properties. These phenomena manifest themselves at temperatures much lower than the ambient one, conditions in which materials are dominated by quantum physics and statistical mechanics. Our main interest involves phenomena such as superconductivity, strong magnetism, and spin ordering effects.

Our group is based on the synergy of two experimental research subgroups: the materials synthesis and characterisation lab led by Prof. Maeno, and the NMR group led by Prof. Ishida. Seminars, scientific discussions, and laboratory activities are conducted jointly by the two groups.

1. Topological superconductors such as Sr2RuO4

Sr2RuO4 is one of the most actively studied superconductors in our laboratory. Our aim is to elucidate the long-standing mystery of its superconducting state by high-purity single crystal growth and precise measurements of electronic transport and magnetism.

2. Material synthesis

New materials are a crucial aspect to discover novel physical phenomena.
In our laboratory, we have succeeded in the synthesis of a large number of materials by the floating zone and flux methods. Notable materials grown in our lab include the superconductor Ag5Pb2O6, the quasi-two-dimensional conductor PdCoO2, the superconductor with broken inversion symmetry CaIrSi3, the new superconductor La3Pt4 and the inverse perovskite oxide superconductor Sr3-xSnO.

3. Microdevices by focused ion beam

We use micro fabrication to reveal new quantum phenomena and study novel material properties.

We also perform studies on small devices, where we can define the material geometry and accurately control the distribution of temperature.

4. Nematic superconductivity

Discovery of nematic superconductivity in CuxBi2Se3, a state in which the superconducting Cooper pairs have a spontaneously broken rotational symmetry.

5. Metal-insulator transitions

We use thermal imaging with materials such as Ca2RuO4 to identify the formation of metallic regions (darker) in a matrix of insulating phase (brighter). This technique allows us to study the formation of metallic regions as a function of current drive.

6. Nuclear magnetic resonance (NMR)

NMR is a powerful measurement tool that allows us to measure electronic and magnetic states on the microscopic scale by using nuclear spins. With this technique, we study the electronic states of a wide range of materials ranging from superconductors to magnetic materials.

7. Uranium-based ferromagnetic superconductivity

For a long time, ferromagnetism and superconductivity were considered to be incompatible. The 5f electrons of uranium compounds, instead, have the special characteristic of being responsible at the same time for both ferromagnetism and superconductivity, two states that are considered to coexist.

We reported several experimental results showing the realisation of a spin triplet state due to ferromagnetic fluctuations in UCoGe.

8. Magnetism and quantum critical phenomena

Several interesting magnetic and superconducting states appear near the quantum critical point of materials. Our research aims to investigate the physical properties near quantum critical points aided by pressure and strong electric and magnetic fields.

9. Quantum size effect in nanoparticles

Nanoparticles can be expected to show unique properties, such as magnetism, metal–insulator transitions, that are due to the discrete nature of the quantum energy levels, which are different from bulk materials. We study quantum size effects in materials such as Pt nanoparticles with NMR measurements.