NMR Study ofYbRh₂Si₂
In correlated metallic electron systems,low energy electronic excitations of the ground state can be well described by the Landau Fermi liquid usually. In contrast, a uniformnon-Fermi liquid state is observed in such systems when a quantum critical phase transition(QCPT) takes place at T=0K. We find a new electronic state around the QCPT in heavy fermion compound YbRh2Si2. In this new state, Fermi and non-Fermi liquid states are coexisting to form a mottled electronic state. Interestingly, the mottled state disappears under high magnetic field that drives the system away from the QCPT.
If you have interest, please read the following article: S. Kambe et al., Nature Physics 10, 840 (2014).

NMR Study of CePt₂In₇
Heavy fermion antiferromagnet CePt₂In₇ becomes superconducting by applying pressure of about 3 GPa. We have determined a microscopic T-P phase diagram by ₁₁₅In-NQR/NMR. Consequently, there is a characteristic pressure P*~2.4 GPa of localized-itinerant transition. We have also found that antiferromagnetic structure changes from incommensurate to commensurate around P*. The critical pressure of antiferromagnetism can be estimated to be Pc~3.4 GPa. Between P* and Pc, superconductivity coexists with the itinerant antiferromagnetism.
If you have interest, please read the following article: H. Sakai, Y. Tokunaga, S. Kambe, F. Ronning, E. D. Bauer, and J. D. Thompson, Phys. Rev. Lett. 112 (2014) 206401.

NMR Study of CeCoIn₅
⁵⁹Co nuclear spin-lattice relaxation has been measured for the heavy fermion superconductor CeCoIn₅ in a range of applied fields directed parallel to the c axis. An enhanced normal state relaxation rate, observed at low temperatures and fields just above H_c2(0), is taken as a direct measure of the dynamical susceptibility and provides microscopic evidence for an antiferromagnetic instability. The results are well described using the self-consistent renormalization (SCR) theory for two-dimensional antiferromagnetic spin fluctuations, and parameters obtained in the analysis are applied to previously reported specific heat and thermal expansion data with good agreement.
If you have interest, please read the following article: H. Sakai, S. E. Brown, S.-H. Baek, F. Ronning, E. D. Bauer and J. D. Thompson, Phys. Rev. Lett. 107 (2011) 137001.

NMR Study of AmO₂
The first NMR study of americium dioxide (AmO₂) has been done. More than 30 years ago, a phase transition was suggested to occur in this compound at 8.5 K based on magnetic susceptibility data, while no evidence had been obtained from microscopic measurements. We have prepared a powder sample of ²⁴³AmO₂ containing 90 at. % ¹⁷O and have performed ¹⁷O-NMR at temperatures ranging from 1.5 to 200 K. After a sudden drop of the ¹⁷O NMR signal intensity below 8.5 K, at 1.5 K we have observed an extremely broad spectrum covering a range of ~14 kOe in applied field. These data provide the first microscopic evidence for a phase transition as a bulk property in this system. In addition, the ¹⁷O NMR spectrum has been found to split into two peaks in the paramagnetic state, an effect which has not been reported for actinide dioxides studied up to now. We suggest that the splitting is induced by self-radiation damage from the alpha decay of ²⁴³Am.
If you have interest, please read the following article: Y. Tokunaga, T. Nishi, S. Kambe, M. Nakada, A. Itoh, Y. Homma, H. Sakai and H. Chudo, J. Phys. Soc. Jpn. 79, 053705 (2010).

NMR Study of CeIrIn₅
Based on analysis of nuclear (¹¹⁵In) spin-lattice relaxation-time measurements on the heavy-fermion superconductor CeIrIn₅, (q, ω, T)-dependences of the dynamical susceptibility Imχ(q, ω) near the antiferromagnetic wave vector Q at low energy ω ~ 0.0001 meV have been estimated. The T-behaviors found, Imχ(q, ω) ~ T^-3/2 and antiferromagnetic correlation length ξ ~ T^-3/4, are consistent with quantum critical behavior for a three-dimensional antiferromagnet (d=3, z=2) having a spin-density-wave instability.
If you have interest, please read the following article: S. Kambe, H. Sakai, Y. Tokunaga and R.E. Walstedt, Phys. Rev. B 82, 144503 (2010).

μSR Study of PrPb₃
We revealed that a positive muon implanted into f-electron compound PrPb₃ forms a novel spin system Pr - μ⁺ - Pr together with nearest neighbor Pr nuclear spins by means of μ⁺SR. The interaction between the spins is mediated by f-electrons, which is completely different from that in previously reported a-few spin systems made up of a μ⁺ spin and nuclear spins.
If you have interest, please read the following article: T. U. Ito, W. Higemoto, K. Ohishi, N. Nishida, R. H. Heffner, Y. Aoki, A. Amato, T. Onimaru, and H. S. Suzuki, Phys. Rev. Lett. 102, 096403 (2009).