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Antiferromagnetic nuclear magnetic resonance (AFNMR) of the Cu(2) site and the Cu-NQR of the Cu(1) site are investigated as a function of excess oxygen, y, in Pb 2 Sr 2 ( Y 1− x Ca x ) Cu 3 O 8+ y . We confirm the re-appearance of the antiferromagnetic order of the Cu(2) moments and the change of the valence of the Cu(1) site with hole-doping introduced by extra oxygen in the superconducting Pb 2 Sr 2 ( Y 0.5 Ca 0.5 ) Cu 3 O 8+ y .

From anomalies of the heat capacity and the thermal expansion, the structural phase boundary of the LTT-LTO transition is determined in the narrow range around x=0.12 of La 2−x Ba x CuO 4 , where superconductivity is suppressed remarkably. The widely-spread CuNQR spectra and the decay of the asymmetry parameter of μSR are indicative of the magnetic order of Cu moments in the LTT phase where the induced charge transfer between Cu and O atoms causes the localization of the electronic state and the increase of magnetic moments at the Cu site.

Hyperfine field at the Cu(2) site and quadrupole frequencies of both the Cu(1) and Cu(2) sites in RBa 2 Cu 3 O 6 and RBa 2 Cu 3 O 7 (R is a rare earth element) obtained from the Cu-NQR and antiferromagnetic nuclear resonance (AFNMR) are summarized as a function of the rare earth ionic radius.

Magnitude −S of onsite Cu magnetic spin and temperature linear term γ T fo La2−x(Sr,Ba)xCuO4 have been determined as a function of x by measuring the low temperature heat capacity below 1 K down to about 70 mK. At the insulator-superconductor boundary of both LaSr and LaBa systems, − S is about 0.4μ B that is about a half of the magnetic moment at x=0. − S of LaSr superconductor decreases with increasing x. The LaBa system, however, shows a maximum of − S 0.25 μB and also shows a minimum of the electronic heat capacity at x∼0.12 where a conspicuous dip in Tc−x phase diagram was observed.

Low temperature heat capacity was measured as a function of x in Pr 2−x Ce x CuO 4 . The temperature linear term, γT, increases linearly, and the Debye temperature decreases with x. The Einstein contribution to the heat capacity is large and decreases gradually with electron-doping.

For La 2−x Sr x CuO 4 superconductor (0.06 n T in the normal state was estimated from the heat capacity jump at T c . With increasing x, γ n shows a steep increase up to x∼0.15 and attains to be about 9mJ/K 2 /mol. This is the same magnitude as the coefficient of the γT-term observed in the metallic state (x>0.25) at 0.6

The Cu-NQR spectra are observed in the wide range of x in La 2−x Sr x CuO 4−y . The change of oxygen coordination to Cu atoms causes the large difference of EFG at the Cu site. Nuclear relaxation rates T 1 −1 and T 2 −1 are enhanced remarkably for x c superconductivity appears, and suppressed largely for x>0.4. The temperature dependence of T 1 −1 for x>0.4 obeys the Korringa relation in the normal state. The NQR results suggest that the antiferromagnetic spin fluctuations are suppressed by hole-doping for x>0.4, but superconductivity appears in the presence of antiferromagnetic spin fluctuations for x

Antiferromagntic order of Cu moments is confirmed by the observation of zero field Cu-NMR for x

Pulsed NMR study of 11 B has been performed in GdRh 4 B 4 and SmRh 4 B 4 at frequencies of 1–10 MHz and at 50 mK–300 K. From the isotropic Knight shift, we obtained the conduction electron spin polarization at B site. T 1 in paramagnetic state is explained by the dipolar and RKKY coupling between 11 B and the rare earth (RE) moments which are modulated by the RE-RE exchange interaction and the s-f interaction. Below the magnetic transition temperature both the line width and T 1 increase, which is associated with the magnetic ordering. In SmRh 4 B 4 NMR measurement was made in antiferromagnetic and superconducting states. Appreciable difference in T 1 was not observed between normal and superconducting state.

The low temperature specific heat was measured in βMn metal and alloys with V, Cr, Fe, Co and Ni. The large enhancement of the electronic specific heat due to spin fluctuations is observed. The coefficient of the electronic specific heat, γ, changes with the excess number of the d electrons per atom in the alloy, Δ n d , having a peak at Δ n d =0.005 which indicates that pure βMn remains paramagnetic even at 0 K. The behavior of the electronic specific heat is explained well qualitatively by the self-consistently renormalized spin fluctuation theory by Hasegawa.

NMR measurements on 51 V and 93 Nb impurities in Pt and Pd host metals were carried out using both CW and pulsed NMR techniques. Line width, Knight shift and nuclear magnetic relaxation time were measured at temperatures between 4.2 and 1.2 K. Marked result is strong reduction of nuclear spin-lattice relaxation rate of impurity nuclei compared with that in bulk V or Nb metals. From the observed results on the Knight shift and the spin-lattice relaxation rate, it is concluded that the local density of states at the impurity sites are severely reduced compared with that in bulk. Comparison with the theoretical calculations is briefly given.

Pulsed NMR study has been performed in RERh 4 B 4 (RE=rare earth). We obtained the conduction electron spin polarization at B site from the isotropic Knight shift of 11 B. The isotropic shift is proportional to ( g J -1)/ g J , which means J sf N s ( E F ) is nearly same for all RERh 4 B 4 compounds. The nuclear spin lattice relaxation time, T 1 of 89 Y and 103 Rh were measured in YRh 4 B 4 and LuRh 4 B 4 . The density of state at the Fermi level in each atomic site is evaluated from T 1 . The agreement of the results with the recent band calculation is satisfactory. The isotropic shift of 103 Rh is measured in SmRh 4 B 4 .

Nuclear quadrupole resonance (NQR) of 139 La in La 2- x Ba x CuO 4 has revealed an unexpected enhancement of nuclear relaxation rates, 1/ T 1 and 1/ T 2 , with Ba-doping in the low-temperature region, suggesting the occurrence of magnetic instability at T c * ∼10 K. The remarkable pressure dependence of 1/ T 1 below T c * is sharply in contrast to the pressure independence of 1/ T 1 above T c * . At high pressures, the relaxation rates are remarkably enhanced below T c * , increasing proportionally with decreasing temperature.

Pulsed NMR study of 11 B has been performed in DyRh 4 B 4 and Dy(Ir 0.7 Rh 0.3 ) 4 B 4 at the resonance frequencies of 10–17 MHz and at temperatures of 0.5 K–300 K. From the nuclear spin lattice relaxation time T 1 , we obtain JN ( E F ) at Dy site. The crystal field effect on Dy is also investigated. A probable spin structure of the antiferromagnetic Dy(Ir 0.7 Rh 0.3 ) 4 B 4 is also proposed from the zero-field NMR spectrum of 11 B, whose hyperfine field is generated by the classical dipole interaction with RE element.

In order to examine the nature of non-transitional impurities in transition metals, we have investigated the superconducting and normal state properties of alloys of Vanadium with Cu, Al, Si and Sn through measurements of the low temperature specific heat, magnetic susceptibility and electrical resistance. The superconducting transition temperature T c was found to decrease rapidly with concentration of the non-transition element in each alloy system. The electronic state density at the Fermi level, N (0), is only slightly affected at small impurity concentrations (few at %) but decreases monotonically for larger concentrations, the rate of decrease being larger for non-transition elements with larger valence numbers. The Debye temperature was found to remain approximately constant. Based on these results, the correlation between the change in the electronic state and superconducting properties have been examined. An interesting correlation has been revealed between the rate of decrease of T c and recent ...

The heat capacity of La/sub 2-//sub x/Ba/sub x/CuO/sub 4/ was investigated between 0.8 and 10 K. The linear temperature term ..gamma..T of the heat capacity is absent in the antiferromagnetic-ordered region of xless than or equal to0.02. ..gamma.. increases abruptly from x = 0.02 to x = 0.04 where the system is still insulating at low temperature, and seems to saturate at the order of 5 mJ/mol K/sup 2/ in the superconducting region of xgreater than or equal to0.05. The correlation between magnetic order and vanishing ..gamma..T term and the existence of a finite ..gamma..T term for Ba doping give support to the resonating-valence-bond picture.

The nuclear spin-lattice relaxation rate, 1/T1, of Cu-NQR in La2−xSrxCuO4 is suppressed by superconductivity without the BCS type enhancement just below Tc, while its temperature dependence obeys the Korringa relation below 100 K in the normal region. The clear changes of the enhancement of 1/T1 and 1/T2 and also of the profile of the Cu-NQR spectra are observed with increasing x beyond x=0.3∼0.4, suggesting the change of the electronic state of the La-system around x=0.3∼0.4. The anomalies of relaxation and intensity of Cu-NQR near x=1, where the electronic state is again localized, seems to be newly suggestive of magnetic order.

Electric resistivity, a.c. magnetic susceptibility, magnetization and 157 Gd NMR measurements have been performed in (Ce 1- x Gd x )Ru 2 for x =0.12 and 0.13. The resistivity measurement determines the superconducting transition temperature for x =0.12 and 0.13 to be 4.85 K and 4.4 K, respectively, though both the susceptibility and magnetization show no diamagnetism. An internal field associated with the ferromagnetic order appears in 157 Gd NMR, where the nuclear spin-lattice relaxation time for x =0.12 below 100 mK shows a characteristic temperature dependence for the superconductivity. From these results, it is concluded that the compound with x =0.12 is microscopically in a coexistent state of the superconductivity and the ferromagnetism at low temperature, forming a self-induced vortex state.

Pulsed NMR studies of 59 Co and 11 B have been performed in a series of antiferromagnetic RECo 4 B 4 compounds (RE=Gd, Tb, Ho, Er, Tm) in both paramagnetic and magnetically ordered states. In the paramagnetic state, NMR signals of both 59 Co and 11 B were observed only in GdCo 4 B 4 in the temperature range of 77–300 K. From the isotropic Knight shift measurement, we obtained the conduction electron spin polarization at both Co and B sites generated by the d - f exchange interaction on the rare earth site. The electron spin polarization estimated in RECo 4 B 4 is about twice as large as that in RERh 4 B 4 system. In the antiferromagnetic state, zero-field resonances of 59 Co and 11 B were observed for GdCo 4 B 4 , TbCo 4 B 4 and DyCo 4 B 4 at 1.3 K. From the hyperfine fields and NMR spectra, the spin structure is shown to be the same type as in the antiferromagnetic superconductor Ho(Rh 0.3 Ir 0.7 ) 4 B 4 .

Nuclear quadrupole resonance (NQR) of 139La has been performed to study magnetic properties of La2-xBaxCuO4 between 1.4 and 250 K. The pronounced enhancement of nuclear relaxation rates of 1/T2 and 1/T1 are obtained for 0.01

We have successfully prepared PrRh 4 B 4 and CeRh 4 B 4 with the CeCo 4 B 4 -type structure under high pressure and at high temperature. PrRh 4 B 4 shows a superconducting transition at 4.6 K and the upper critical field H c 2 at 0 K is found to be 6.8 kG. The temperature dependence of the upper critical field indicates no re-entrant superconductivity down to 1. 4 K. CeRh 4 B 4 does not show superconductivity nor any magnetic ordering down to 1.4 K. The lattice parameters of CeRh 4 B 4 suggest the valence of 3.4 for cerium.

The heat capacity of La 2− x Sr x CuO 4 for the Sr-concentrations 0⩽ x ⩽0.3 was measured in the wide temperature range between 60 K and 80 mK. A homogeneous bulk superconducting transition was characterized by a steep jump of the heat capacity at T c , Δ C/T c =13 mJ/K 2 /mol for x =0.15. The low temperature heat capacity below ∼ 0.5 K. shows nuclear Schottky anomaly due to the 63 65 Cu nuclei, from which we obtained the Sr-concentration dependence of the hyperfine field on the 63 65 Cu nuclei. The result shows the static magnetic order of the Cu-moments in the oxide superconducting La-system.

NMR of Co 59 has been performed in ferromagnetic PdCo alloys. The internal field changes from -215 kOe in pure Co metal to 230±5 kOe in alloys of Co diluted in Pd. The results are consistent with the previous measurements by nuclear polarization and Mossbauer effect experiments. The line width is very broad in alloys with low Co concentration. Even in 0.5% Co alloy, the width still has the value of 50 MHz. T 2 shows rapid decrease with decreasing Co concentration. The experiment has also been performed on Co 59 in ferromagnetic Pd x Ni 1- x Co system. The results are quite similar to those in PdCo alloys.

Nuclear quadropole resonance (NQR) of 139 La is investigated in variously oxygenated La 2 CuO 4− y . The saturated internal magnetic fields at the La site are invariant against defects of the crystal, suggesting that sublattice moments of Cu spins at the ground state do not change with the amount of oxygen deficiencies. On the contrary, the antiferromagnetic transition temperature, T N , depends on the oxygen deficiencies. In the low temperature region below 70 K, the enhancement of the nuclear relaxation rates, 1/ T 1 , is strongly correlated with the decrease of T N .

Nuclear quadrupole resonance (NQR) of 139 La has been performed to study the electronic and magnetic properties of La 2- x Ba x CuO 4 between 1.5 and 240 K. The temperature dependence of the separation of the double peaks in spectra clearly indicates the magnetic ordering in the small x region. The internal fields at La sites due to magnetic order largely decrease with Ba concentration. The divergence of 1/ T 2 indicates that another phase appears at low temperatures. The electric field gradient changes on passing from the normal to the superconducting states, indicating the apparent influence of superconductivity on the electronic state at La sites in this system.

The low temperature specific heat of Th-Y and Th-La alloys have been measured in order to compare with that of La-Y alloys. The change of the Debye temperature of Th-Y alloys with Yttrium concentration is very similar to that of La-Y alloys. The atomic property of McMillan-Hopefield's parameter η is also discussed.

The heat capacity of nominal composition of BiBaCaCu 2 O y has been measured between 2 and 10 K. The resistivity of the sample decreases linearly with decreasing temperature and tends to zero at 65 K. No appreciable T -linear term, γ T , and upturn behavior in the heat capacity is obtained at low temperature down to 2 K.

Pulsed and cw-NMR measurements of 11 B have been used to study the spin dynamics of magnetic rare earth ions in (Y 1- x RE x )Rh 4 B 4 . We find the nuclear spin-lattice relaxation rate of 11 B induced by RE = Tb, Dy and Ho moments to be exponential in -Δ/ T in the normal state, where Δ is the crystal field splitting of the first excited state. Anomalous temperature dependencies of the transverse relaxation time T 2 , Knight shift and NMR line width in (Y 1- x Dy x )Rh 4 B 4 are obtained in the temperature region where T 1 changes drastically. The results are discussed in terms of a model of the crystalline electric fields, in which thermal activation across Δ must take place for the Δ m J = ±1 transition to occur in highly anisotropic paramagnetic moments in the ternary superconductors.

Hyperfine fields of 11 B in ferromagnetically ordered Gd-, Tb-, Dy- and HoRh 4 B 4 have been measured by an NMR in zero-field experiment. The hyperfine fields are explained as a sum of the dipolar field from the surrounding R E ion, the conduction electron polarization via s-f exchange interaction and the Lorentz field. A preliminary experiment in (HoEr)Rh 4 B 4 has also been made.

Electron microscopy of the turtle sinus venosus shows an unusual neuron soma which is immediately surrounded by myocardial cells so as to form a somato-muscular complex. Studies of 36 sections cut through this neuron soma indicate that 27.4% of the somal surface studied is directly covered by cardiac muscle cells without any intervening basal lamina. Similarly, 18.8% of the somal surface studied is in contact with unmyelinated axons which at places make typical axosomatic synapses. A coupling of peripheral cisterns of the sarcoplasmic reticulum and the sarcolemma exists at the somato-muscular contiguity as well as at the border between cardiac muscle cells. It is suggested that neural influences upon the pacemaking activity of the turtle heart sinus can well be exerted through the somato-muscular pathway. Additionally, an axon which is presynaptic to the neuron soma has been observed to be simultaneously in a synaptic relation with a cardiac muscle cell; a remarkable deviation from the classical picture of the efferent nervous outflow to the heart.

The freeze-fracture replication technique was used to study the mechanoreceptive digital corpuscles in toe pads of mice. The axon terminal plasmalemma had intramembranous particles (IMPs) at a density of 2367 +/- 517 microns-2 (mean +/- S.E.M.) in the P-face and 84 +/- 4 microns-2 in the E-face. Particles were 10 +/- 1.8 nm in diameter in the P-face and 10 +/- 1.5 nm (mean +/- S.D.) in the E-face. Particle-rich and particle-free areas were noted in the P-face. The lamellar cell plasmalemma had IMPs at a density of 3359 +/- 224 microns-2 in the P-face and 265 +/- 95 microns-2 in the E-face. Particles were 10 +/- 1.4 nm in diameter in the P-face and 10 +/- 1.6 nm in the E-face. Non-terminal unmyelinated fibres in the connective tissue compartment of toe pads were also examined: the P-faces of the axolemma and Schwann cell plasmalemma had IMPs at a density of 1356 +/- 283 microns-2 and 1514 +/- 514 microns-2, respectively, while the E-face of these membranes had only a few particles. Particles were 9 +/- 1.2 nm and 10 +/- 1.6 nm in diameter in the P-faces of axon and Schwann cell plasmalemmata, respectively. The results show that the IMPs in terminal axolemma and in lamellar cell plasmalemma have a much higher density than those of non-terminal axons or Schwann cells in myelinated and unmyelinated fibres. In addition, IMPs in the terminal axolemma are larger than those in non-terminal axolemma except for the nodal axolemma. It can be said that plasmalemmata of both the axon terminals and lamellar cells of digital corpuscles are specialized in terms of IMPs, suggesting that they have specific physiological properties in mechanoreceptive functions including mechano-electric transduction.

We have successfully prepared PrRh 4 B 4 and CeRh 4 B 4 with the CeCo 4 B 4 -type structure under high pressure and at high temperature. PrRh 4 B 4 shows a superconducting transition at 4.6 K and the upper critical field H c 2 at 0 K is found to be 6.8 kG. The temperature dependence of the upper critical field indicates no re-entrant superconductivity down to 1. 4 K. CeRh 4 B 4 does not show superconductivity nor any magnetic ordering down to 1.4 K. The lattice parameters of CeRh 4 B 4 suggest the valence of 3.4 for cerium.

The zero-field Cu-NMR of Nd 2−x Ce x CuO 4−y around 60–140MHz indicates clearly that antiferromagnetism of Cu spins is situated near superconducting phase. Three distinct components of the NMR signals are observed with large difference in electric quadrupole interactions, showing that local electronic configurations at Cu sites changes significantly with electron-doping.

Cu-NQR spectra in the paramagnetic region of Bi2Sr2(Ca1−xYx)CuO8+y spread over a wide frequency range between 18 and 32MHz, showing the large distribution of the electrical field gradient at Cu sites, reflecting the structural modulation in this system. In the Y-concentrated region, the observation of the antiferromagnetic nuclear resonance (ANFR) of Cu nuclei around 60–130MHz indicates that antiferromagnetism of Cu spins is situated near the superconducting phase.

Nuclear spin lattice relaxation time, T 1 , and the Knight shift of V 51 in V-cu, V-Al and V-Sn alloys are measured. T 1 T increases with the concentration of Cu, Al and Sn. The increase in V-Cu alloy is smaller than that in Al and Sn alloys. The Knight shifts in the alloys do not change. The change of T 1 T indicates the decrease of the density of state of the conduction electrons at the Fermi level at V site as observed in the measurements of the specific heat, the magnetic susceptibility and the superconducting transition temperature in these alloys.

A small specific heat jump at superconducting transition in YRh 4 B 4 and small magnetic contribution to the entropy in magnetically ordered state in RRh 4 B 4 (R=Tb, Dy, Ho and Er) have been observed. Hyperfine field of Gd in GdRh 4 B 4 is largly anisotropic forming a powder pattern in NMR spectrum. The broadened NMR spectra of 11 B are observed in the magnetically ordered compounds. The polarization of the conduction electrons at B site is found to be very small.

Spin echo NMR and ac susceptibility measurements have been performed at 60 mK∼4.2 K in (Ce 1- x Gd x )Ru 2 . The sharp superconducting transition is confirmed for x ≦0.110. The NMR signals associated with the ferromagnetically ordered Gd atoms are observed down to x =0.105 in zero external field and to x =0.095 with applying field. The hyperfine field at Gd site changes as -206+88· x kOe. The intensity of the signal in zero field decreased rapidly in accordance with the appearance of superconductivity. The temperature, concentration and external field dependence of the transverse relaxation time T 2 show that T 1 is governed mainly by the Weger mechanism. The rapid increase of T 1 with lowering temperature for 0.105≦ x ≦0.110 indicates a possible appearance of small energy gap associated with superconducting state. The results support the coexistence of superconductivity and ferromagnetism.

The heat capacity of La 2-x Sr x CuO 4 for 0 63/65 Cu nuclei, from which we obtain the x-dependence of the hyperfine field of Cu nuclei. The result shows the static magnetic order of Cu-moments in the superconducting La-system.

The nuclear spin-lattice relaxation rate, 1 T 1 , of Cu NQR in La 2−x Sr x CuO> 4 is suppressed by superconducting energy gap for 0.12 1 T 1 and 1 T 2 and also the profile of the spectra take place with increasing x beyond about x =0.3, indicating the strong correlation of high-T c superconductivity and the antiferromagnetic fluctuations of Cu spins.

Temperature dependence of the nuclear relaxation rate of both Cu(1) and Cu(2) sites indicates the appearance of the magnetic order without destroying superconductivity in the Fe-doped YBa2Cu3O7. The impurity-induced antiferromagnetism of Cu moments is verified also by the observation of the antiferromagnetic Cu NMR around 70–110MHz in this system.

NMR of 55 Mn in (Pd 0.996 Co 0.004 ) 1- x Mn x alloys in a giant moment ferromagnetic and a spin glass state has been observed down to 100 mK. The narrow NMR line at about 405 MHz shifts slightly to lower frequency side with x for x ≧4%, which indicates a partial cancellation of the contribution of hyperfine field from the neighboring impurities in the spin glass state. No abrupt change in the relaxation time has been found through the phase change from the ferromagnetic to the spin glass state.

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.