Taiichiro Haseda

The Magnetic Properties of Cupric Formate Tetrahydrate at Low Temperatures

The magnetic susceptibility of single crystals of Cu(HCO 2 ) 2 ·4H 2 O was measured at temperatures between 1.4°K and 80°K by a. c. bridge and magnetic balance method. This salt is an example of the magnetic two dimensional lattice. The interaction between Cu 2+ ions is mainly the superexchange interaction through a formate ion in the same layer. From the Weiss constant of about -150°K, it is concluded that strength of superexchange interaction through a formate molecule, –(O–CH–O)–, has the same order as that through one diamagnetic atomic ion such as –(Cl)–. The existence of a broad maximum of the susceptibility at about 60°K implies the appearence of short range order in the two dimensional lattice. The antiferromagnetic transition accompanied by parasitic ferromagnetism was found at 17.0°K±0.2°K. The weak ferromagnetic moment in L 1 L 2 plane was about 150 c.g.s.e.m.u. at 0°K. Along L 3 axis, no ferromagnetic moment was found. The susceptibility of isomorphous Cu(HCO 2 ) 2 ·2H 2 O·2(NH 2 ) 2 CO was si...

Paramagnetic Susceptibility of CoCl2·6H2O and its Deuterated Salts

The paramagnetic susceptibility of a single crystal of CoCl 2 ·6H 2 O was measured by the usual a-c bridge method. Transition to the antiferromagnetic state was observed at about 3.3°K. The easy axis is along the crystalline c axis. The g values determined in the paramagnetic region, below 20°K are: g c = g b =4.9 and g c ⊥ =2.9. Some considerations about the anisotropic susceptibilities in the paramagnetic state are given from the standpoint of crystalline field theory. The exchange interaction in this salt is discussed considering the interaction path between the magnetic ions which involves the linkages of chlorine atoms or water molecules. The measurements on the deuterated salts are intended to make clear the effect of the hydrogen bond on the magnetic exchange interaction.

Studies on the Linear Antiferromagnets : Magnetic Susceptibilities of Cupric Quinone Complex Salts at Low Temperatures

The magnetic susceptibilities of three Cu quinone complex salts were measured at low temperatures. These salts, Cu–Q–H, Cu–Q–Cl and Cu–Q–Br, are considered to have structure of magnetic one dimensional lattice. Cu–Q–H is obtained in the form of stick-like colloid whose length is shorter than a few thousand A. Some characteristics of the antiferromagnetic linear chain were found in Cu–Q–H. At the lowest temperatures, the end effect and the odd or even number effect were examined. The length of the chain of Cu–Q–H is estimated to have the number of Cu 2+ ions more than 9. The super-exchange interaction in a chain of each salt passes through the intervening quinone-molecule. The coupling constant J between nearest neighboured Cu 2+ ions in Cu–Q–H was estimated to be between k (-14°K) and k (-24°K). The large Js of three salts may be attributed to the superexchange interaction through the quinone-molecule.

Paramagnetic Susceptibility of Single Crystals of Some Nickel Salts

Paramagnetic susceptibility of single crystals of NiK Tutton salt and NiCl 2 ·6H 2 O were measured in the temperature range between 1.40°K and 20.4°K. The anisotropic susceptibilities found in NiK Tutton salt are in very good agreement with the calculated values using the splitting parameters which are determined by paramagnetic resonance experiment. In NiCl 2 ·6H 2 O, the antiferromagnetic transition was found at about 6°K. The easy axis is along the axis perpendicular to crystalline c axis in a c plane.

The Paramagnetic Susceptibility of Some Nickel Salts

Paramagnetic susceptibilities of some nickel salts were measured in the temperature range between 1.40°K and 290°K. The flat behavior of the susceptibility v s temperature curve in the lowest temperature region was especially prominent in NiCl 2 ·6H 2 O. The paramagnetic susceptibility of a powdered specimen of the nickel salt was calculated with the low field approximation. The characteristic behavior of a nickel ion in various salts was explained as due to the Stark splitting of the lowest spin triplet. The measured values of susceptibility were analysed and consistent results were obtained. Especially in NiCl 2 ·6H 2 O, the crystalline field was expected to be much deformed from cubic symmetry and this is consistent with the fact that the paramagnetic resonance could not be detected at 9800 and 18000 Mc/sec in this salt.

The Superexchange Interaction between Cr +3 pair in Chromium Bi-nuclear Complex Ions

The investigation of the magnetic properties of chromium bi-nuclear complex compounds was made. The results of the magnetic susceptibility measurements were analyzed on the assumption that their magnetic behaviours are determined mainly by the superexchange interaction between two Cr +3 ions in the same complex unit. The coefficient of the superexchange interaction J was estimated to be about -30 k in the cases of [(NH 3 ) 5 Cr–OH–Cr(NH 3 ) 5 ] +5 and [(NH 3 ) 5 Cr–OH–Cr(NH 3 ) 4 OH] +4 complex ions. In the case of [(NH 3 ) 5 Cr–O–Cr(NH 3 ) 5 ] +4 , the susceptibility is very small below room temperature, hence a large absolute value of J is required to account for the experimental result. The susceptibility of [Cr(NH 3 ) 5 Cl]Cl 2 which is a usual mononuclear complex salt, was measured for the sake of comparison with the above mentioned bi-nuclear complex salts. The susceptibility obeys in this case the Curie-Weiss law in the range between 2.5°K and room temperature. The Weiss constant \(\varTheta\) is -...