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We present 115In NMR results in a novel high magnetic field and low temperature phase of CeCoIn5 where exotic superconductivity coexists with the incommensurate spin-density wave order. The quantitative analysis for the field evolution of newly-emerged low-energy quasiparticle density of states is consistent with the nodal plane formation which is expected in the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state. The NMR spectra also suggest that the spatially uniform spin-density wave is induced in the FFLO phase.

Static and dynamical properties of Fe3+ (3d5; S = 5/2) spins in geometrically frustrated magnetic molecule Fe30 have been investigated by nuclear magnetic resonance (NMR) in the temperature range T = 0.1–300 K From a measurement of nuclear spin-lattice relaxation rates as a function of temperature, the fluctuation frequency of Fe3+ spins is found to decrease with decreasing temperature, indicating spin freezing at low temperatures.

Static and dynamical properties of Cu2+ (3d9; S = 1/2) spins in a twisted Heisenberg triangular spin tube, [(CuCl2tachH)3Cl]Cl2, have been investigated by nuclear magnetic resonance (NMR) and magnetization measurements in the temperature range T = 0.05-300 K. Magnetization curves below 0.5 K show a clear change in slope around 5 T, attributed to a signature of 1/3 plateau in magnetization. From a systematic measurement of nuclear spin-lattice relaxation rates as a function of temperature and external field, the fluctuation frequency of Cu2+ spins is found to decrease with decreasing temperature, revealing an unusual slow spin dynamics at low temperatures.

We show that intramolecular exchange disorder recently found in the geometrically frustrated magnetic molecules {Mo(72)Fe(30)} and {Mo(72)Cr(30)} leads, in a classical Heisenberg model description, to spin freezing and slow magnetization dynamics reminiscent of spin glass behaviour. Also we suggest that our low temperature and low magnetic field nuclear magnetic resonance (NMR) measurements on {Mo(72)Fe(30)}, showing rapid and strong broadening of the proton line width on cooling below 600 mK, are evidence for a crossover from paramagnetic behaviour to a frozen spin configuration. Similar broadening is observed in {Mo(72)Cr(30)}. This observed effect is consistent with our theory of spin freezing and slow magnetization dynamics in these systems due to exchange disorder.

Static properties of Cu2+(3d9; S=1/2) spins in a new class of quantum spin system, a twisted Heisenberg triangular spin tube, [(CuCl2tachH)3Cl]Cl2, have been investigated by using nuclear magnetic resonance (NMR) in a temperature region of T=0.05?300 K. An observation of magnetic broadenings of 1H-NMR spectrum at low temperatures directly revealed a gapless ground state of the system.

We study the NMR of newly-discovered superconducting state of CeCoIn5 in a perpendicular field (H ⊥ ab) as well as in a parallel field (H || ab), Upon entering the new SC state at high field and low temperature region, NMR spectra change dramatically below T(HC) in the case of H ⊥ ab as well as H || ab. A well-separated spectrum for H ≥4.7 T persists down to the lowest temperature, which indicates the appearance of a nodal plane structure as expected for Fulde-Ferrell-Larkin-Ovchinnkov (FFLO) state. We find the critical field HFFLO⊥ separating the FFLO and the BCS state lies in a very narrow range between 4.65 T and 4.70 T below TC(H).

Motional state of 3He in Na–Y zeolite, that has a three-dimensional (3D) network of the channels only about 10 A in diameter, has been studied by pulsed NMR. At the adsorbed amount 60% of full channel, we measured a self-diffusion coefficient of the a atom at 25>T>2 K. The magnitude and the temperature dependence of the coefficient quite resemble those of bulk liquid 3He. The resonance frequency dependence of T1, suggests a 3D fluid at T>5 K and a 2D fluid at the lower temperatures.