Dr. Masahiko Isobe

 

Dr. Masahiko Isobe

Max-Planck Institute for Solid State Research
Heisenbergstr. 1, D-70569 Stuttgart, Germany

ph.: +49 (0)711 689 1509
fax: +49 (0)711 689 1502

email: m.isobe@fkf.mpg.de

Research Topics

 

Vanadium oxides

  • α’-NaV2O5 : novel charge order system
  • γ-LiV2O5 : S = 1/2 quasi 1D system
  • CaV2O5 : two-leg spin ladder system
  • MgV2O5 : two-leg spin ladder system
  • CsV2O5 : dimer system
  • Na9V14O35 : 2D spin gap system
  • β-Sr0.33V2O5, β-Ca0.33V2O5 : charge order system
  • K2V8O16, Rb2V8O16 : metal-insulator transition (charge ordering)
  • ( RbVO3, CsVO3 : white-light-emitting device )

Titanium oxides

  • NaTiSi2O6 : orbital-driven Peierls transition
  • MgTi2O4 : metal-insulator transition (orbital-Peierls transition)

Chromium oxides

  • CaCrO3 : antiferromagnetic metallic oxide
  • K2Cr8O16 : ferromagnetic metal (or half-metal) to insulator transition
Selected publications:
 Vanadium Oxides
 
"Magnetic susceptibility of quasi-one-dimensional compound NaV2O5- Possible spin-Peierls compound with high critical temperature of 34K-", M. Isobe and Y. Ueda, J Phys Soc Jpn 65 (1996) 1178-1181.
"Magnetic susceptibilities of AV2O5 (A = Li and Cs) with square pyramidal V(IV)O5", M. Isobe and Y. Ueda, J Phys Soc Jpn 65 (1996) 3142-3145.
"Crystal growth of new spin-Peierls compound NaV2O5.", M. Isobe, C. Kagami and Y. Ueda, J Crystal Growth 181 (1997) 314-317.
"Effect of Na-deficiency on the spin-Peierls transition in NaV2O5", M. Isobe and Y. Ueda, J Alloys Compds 262 (1997) 180-184.
"Observation of a spin gap in MgV2O5 from high field magnetization measurements", M. Isobe, Y. Ueda, K. Takizawa and T. Goto, J Phys Soc Jpn 67 (1998) 755-758.
"Crystal structure and magnetic properties of Na9V14O35: Sodium-vanadium bronze NaxV2O5", M. Isobe, Y. Ueda, Y. Oka and T. Yao, J Solid State Chem 145 (1999) 361-365.
"Physical properties of vanadium oxide bronzes A0.33V2O5 (A = Ca and Sr)", M. Isobe and Y. Ueda, Mol Cryst Liq Cryst 341 (2000) 1075-1080.
"Observation of Metal-Insulator Transition in Hollandite Vanadate, K2V8O16", M. Isobe, S. Koishi, N. Kouno, J. Yamaura, T. Yamauchi, H. Ueda, H. Goto, T. Yagi and Y. Ueda, J Phys Soc Jpn 75 (2006) 073801
"Direct fabrication of metavanadate phosphor films on organic substrates for white-light-emitting devices", T. Nakajima, M. Isobe, T. Tsuchiya, Y. Ueda and T. Kumagai, Nat. Mater. 7 (2008) 735-740.
"Dimerization and Charge Order in Hollandite K2V8O16", A. C. Komarek, M. Isobe, J. Hemberger, D. Meier, T. Lorenz, D. Trots, A. Cervellino, M. T. Fernandez-Diaz, Y. Ueda, and M. Braden, Phys. Rev. Lett. 107 (2011) 027201-1-4.
 
 Titanium Oxides
 
"Novel phase transition in spin-1/2 linear chain systems: NaTiSi2O6 and LiTiSi2O6", M. Isobe, E. Ninomiya, A. N. Vasil'ev and Y. Ueda, J Phys Soc Jpn 71 (2002) 1423-1426.
"Observation of phase transition from metal to spin-singlet insulator in MgTi2O4 with S=1/2 pyrochlore lattice", M. Isobe and Y. Ueda, J Phys Soc Jpn 71 (2002) 1848-1851.
"Observation of lattice dimerization in spin-singlet low temperature phase of NaTiSi2O6", E. Ninomiya, M. Isobe, Y. Ueda, M. Nishi, K. Ohoyama, H. Sawa and T. Ohama, Physica B 329 (2003) 884-885.
"Synthesis, structure and physical properties of spinel solid solutions Mg2TiO4-MgTi2O4", M. Isobe and Y. Ueda, J Alloys Compds 383 (2004) 85-88.
 
 Chromium Oxides
 
"CaCrO3: An Anomalous Antiferromagnetic Metallic Oxide", A. C. Komarek, S. V. Streltsov, M. Isobe, T. Moller, M. Hoelzel, A. Senyshyn, D. Trots, M. T. Fernandez-Diaz, T. Hansen, H. Gotou, T. Yagi, Y. Ueda, V. I. Anisimov, M. Grueninger, D. I. Khomskii, M. Braden, Phys. Rev. Lett. 101 (2008) 167204-1-4.
"Discovery of ferromagnetic-half-metal-to-insulator transition in K2Cr8O16", K. Hasegawa, M. Isobe, T. Yamauchi, H. Ueda, J. Yamaura, H. Gotou, T. Yagi, H. Sato and Y. Ueda, Phys. Rev. Lett. 103(2009)146403-1-4.
"Peierls Mechanism of the Metal-Insulator Transition in Ferromagnetic Hollandite K2Cr8O16", T. Toriyama, A. Nakao, Y. Yamaki, H. Nakao, Y. Murakami, K. Hasegawa, M. Isobe, Y. Ueda, A.V. Ushakov, D. I. Khomskii, S.V. Streltsov, T. Konishi, and Y. Ohta, Phys. Rev. Lett. 107 (2011) 266402-1-5.
 
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