JAEA
  • help
  • PC | SP
  • JP | EN
          
Refine your search：     
Report No.
 - 
Clear All
Search Results: Records 1-11 displayed on this page of 11
  • 1

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Paramagnetic electron-nuclear spin entanglement in HoCo$$_2$$Zn$$_{20}$$

Kitazawa, Takafumi; Shimura, Yasuyuki*; Onimaru, Takahiro*; Tsuchida, Shun*; Kubo, Katsunori; Haga, Yoshinori; Sakai, Hironori; Tokiwa, Yoshifumi; Kambe, Shinsaku; Tokunaga, Yo

Physical Review Research (Internet), 8(2), p.023009_1 - 023009_14, 2026/04

https://doi.org/10.1103/bzvk-grrv

Journal Articles

Metallization and pressure-induced superconductivity in carrier doped excitonic insulator (Ta$$_{1-x}$$Ti$$_x$$)$$_2$$NiSe$$_5$$

Tsuchida, Shun*; Hirose, Yusuke; Sekikawa, Takuya; Ono, Yoshiaki*; Hirahara, Takuya*; Sano, Sumika*; Kawaguchi, Shogo*; Kobayashi, Shintaro*; Uwatoko, Yoshiya*; Settai, Rikio*

Journal of the Physical Society of Japan, 94(11), p.114703_1 - 114703_7, 2025/10

https://doi.org/10.7566/JPSJ.94.114703
 Times Cited Count：1 Percentile：44.91(Physics, Multidisciplinary)

We investigated the carrier doping effect on an excitonic insulator Ta$$_2$$NiSe$$_5$$ by means of the electrical resistivity $$rho$$ and Hall coefficient $$R_{rm H}$$ using single crystals of (Ta$$_{1-x}$$Ti$$_x$$)$$_2$$NiSe$$_5$$, and band calculation. The excitonic transition temperature $$T_{rm c}$$ is continuously suppressed to 83 K at $$x$$ = 0.104 while preserving the crystal structure. With increasing substitution concentration $$x$$, a semiconducting increment of $$rho$$ and $$R_{rm H}$$ is strongly suppressed and a metallic behavior is observed at $$x$$ > 0.06. Ti substitution can realize an excitonic correlated metallic state. This metallization is explained by the hole doping effect based on the band calculations. Applying pressure to the carrier doped (Ta$$_{1-x}$$Ti$$_x$$)$$_2$$NiSe$$_5$$, we found superconductivity above 2.6 GPa, which is much smaller than that of Ta$$_2$$NiSe$$_5$$ around 8 GPa. The carrier doping induced by Ti substitution favors superconductivity in this compound.

Oral presentation

None

Tsuchida, Shun*; Hirose, Yusuke*; Sekikawa, Takuya; Ono, Yoshiaki*; Settai, Rikio*

no journal, , 

The excitonic insulators have the property that the entire crystal becomes an insulator due to the collective behavior of electrons and holes bound together in the crystal, and they have begun to attract attention as a new physical property. In this study, we focused on Ta$$_{2}$$NiSe$$_{5}$$, which is one of the excitonic insulator candidates, but its synthesis itself is difficult and its physical properties have not yet been clarified. As a result, superconductivity was observed in (Ta$$_{1-x}$$M$$_{x}$$)$$_{2}$$NiSe$$_{5}$$ at x = 0.08 in the high pressure region. The superconducting transition temperature was found to increase with increasing pressure. The phase transition shown in this study may provide new insight into the relationship between exciton insulators and superconductivity.

Oral presentation

Determination of the hyperfine electron-nuclear level scheme in HoCo$$_2$$Zn$$_{20}$$

Kitazawa, Takafumi; Shimura, Yasuyuki*; Onimaru, Takahiro*; Tsuchida, Shun*; Kubo, Katsunori; Haga, Yoshinori; Sakai, Hironori; Tokiwa, Yoshifumi; Kambe, Shinsaku; Tokunaga, Yo

no journal, , 

We determined the electron-nuclear level scheme in the paramagnetic state of the holmium-based cubic compound HoCo$$_2$$Zn$$_{20}$$ using macroscopic thermodynamic probes alone. From magnetization and specific heat measurements, together with detailed analyses, we obtained the crystalline electric field (CEF) parameters, the magnetic exchange constant, and the hyperfine coupling constant between the $$4f$$ magnetic moment and the $$^{165}$$Ho nuclear spin. These refined parameters reveal that the $$Gamma_5$$ CEF ground state is split by the hyperfine coupling, and that the sextet formed through coupling between the effective $$S=1$$ spin of the $$f$$ electrons and the $$I=7/2$$ spin of the $$^{165}$$Ho nucleus constitutes the paramagnetic ground state. Remarkably, the splitting energy width exceeds 1 K at zero magnetic field, underscoring the importance of electron-nuclear spin coupling in strongly correlated electron systems.

Oral presentation

Carrier doping effect of excitonic insulator candidate Ta$$_{2}$$NiSe$$_{5}$$, 5

Tsuchida, Shun*; Hirose, Yusuke*; Sekikawa, Takuya; Ono, Yoshiaki*; Settai, Rikio*

no journal, , 

Exciton insulators have the property that the entire crystal becomes an insulator due to the collective behavior of electrons and holes bound together in the crystal, and are attracting attention as a novel physical property. In this study, we succeeded in growing an element-substituted sample (Ta1-xMx)$$_{2}$$NiSe$$_{5}$$ (M=Ti, Zr, Hf) and found that the electrical resistivity of the high-temperature phase of the sample with a Ti content of 0.06 or more exhibits a metallic behavior. The electrical resistivity of the high-temperature phase behaves metallurgically for samples with a titanium (Ti) content of 0.06 or more. This is in contrast to the pressure effect, which changes from an insulator to a metallic phase discontinuously. Therefore, we also report the results of the electrical resistivity measurement under pressure of (Ta1-xTix)$$_{2}$$NiSe$$_{5}$$, in which the element substitution effect and the pressure effect exist simultaneously. The phase transition shown in this study is a new insight into the realization of excitonic insulators.

Oral presentation

Carrier doping effect of Ti, Zr, and Hf substitution in excitonic insulator candidate material Ta$$_2$$NiSe$$_5$$

Tsuchida, Shun*; Hirose, Yusuke*; Sekikawa, Takuya; Ono, Yoshiaki*; Settai, Rikio*

no journal, , 

Excitonic insulators have the property that the entire crystal becomes an insulator due to the collective behavior of electrons and holes bound together in the crystal, and they have begun to attract attention as a new physical property. In this study, we focused on Ta$$_2$$NiSe$$_5$$, which is one of the excitonic insulator candidates, but its synthesis itself is difficult and its physical properties have not yet been clarified. The electrical resistivity of M=Ti, Zr, and Hf at low temperatures is 5 to 6 orders of magnitude lower than that of the parent material. Furthermore, when titanium is substituted for tantalum (M=Ti), the electrical resistivity of samples with composition ratio x less than 0.06 is semiconducting, while the electrical resistivity of the high temperature phase behaves metallic when x = 0.06 or higher. The phase transition shown in this study may be a new insight into the realization of excitonic insulators.

Oral presentation

Pressure effects on exciton insulator candidate (Ta$$_{rm 1-x}$$Ti$$_{rm x}$$)$$_{2}$$NiSe$$_{5}$$

Tsuchida, Shun*; Hirose, Yusuke*; Sekikawa, Takuya; Ono, Yoshiaki*; Settai, Rikio*

no journal, , 

Exciton insulators have the property that the entire crystal becomes an insulator due to the collective behavior of electrons and holes bound together in the crystal, and have begun to attract attention as a new physical property. In this study, we focused on Ta$$_{2}$$NiSe$$_{5}$$, which is one of the excitonic insulator candidates, but its synthesis itself is difficult and its physical properties have not yet been clarified. The (Ta$$_{rm 1-x}$$Ti$$_{rm x}$$)$$_{2}$$NiSe$$_{5}$$ sample with x=0.03 exhibits semiconducting behavior at normal pressure, but the temperature Tc, which changes from semiconductor to insulator, decreases monotonically with increasing pressure. On the other hand, the x=0.08 sample exhibits metallic behavior at room temperature, and Tc becomes almost constant at pressures above 0.7 GPa. The x=0.03 sample's Tc behavior is similar to that of the V substitution in the previous study, and the x=0.08 sample is similar to that of the Co substitution in the previous study. The phase transition shown in this study may provide new insight into the realization of excitonic insulators.

Oral presentation

None

Yamashita, Rio*; Tsuchida, Shun*; Sano, Sumika*; Hirose, Yusuke; Settai, Rikio*

no journal, , 

no abstracts in English

Oral presentation

None

Kojima, Ryusei*; Tsuchida, Shun*; Morohashi, Tatsuya*; Saito, Fukumi*; Akino, Seina*; Hirose, Yusuke; Settai, Rikio*

no journal, , 

no abstracts in English

Oral presentation

Carrier doping effect of excitonic insulator candidate Ta$$_{2}$$NiSe$$_{5}$$, 4

Tsuchida, Shun*; Hirose, Yusuke*; Sekikawa, Takuya; Ono, Yoshiaki*; Settai, Rikio*

no journal, , 

Exciton insulators have the property that the entire crystal becomes an insulator due to the collective behavior of electrons and holes bound together in the crystal, and they are beginning to attract attention as a new physical property. In this study, we focused on Ta$$_{2}$$NiSe$$_{5}$$, which is one of the excitonic insulator candidates, but its synthesis itself is difficult and its physical properties have not yet been clarified. Furthermore, when titanium is substituted for tantalum (M = Ti), the electrical resistivity of the sample with composition ratio x less than 0.06 is semiconducting, while the electrical resistivity of the high-temperature phase behaves metallic when x = 0.06 or higher. The phase transition shown in this study may be a new insight into the realization of excitonic insulators.

Oral presentation

Structural study of elemental substituted excitonic insulator Ta$$_{2}$$NiSe$$_{5}$$ using X-ray diffraction

Hirose, Yusuke; Tsuchida, Shun*; Sano, Sumika*; Kawaguchi, Shogo*; Kobayashi, Shintaro*; Omura, Ayako*; Settai, Rikio*

no journal, , 

Ta$$_{2}$$NiSe$$_{5}$$ undergoes a structural phase transition from orthorhombic to monoclinic at Tc~330K and simultaneously becomes an insulator, which attracts attention as one of candidate materials for exciton insulators, and has been actively studied. We have previously demonstrated that element substitution can suppress Tc and cause the system to become metallic. In this study, we aimed to clarify the origin of the change in electronic state due to element substitution by crystal structure analysis, and we performed powder X-ray diffraction experiments on element-substituted Ta$$_{2}$$NiSe$$_{5}$$ at BL02 of SPring-8, and we will report the results.

11 (Records 1-11 displayed on this page)
  • 1