Antiferromagnetic Manganese Research Articles

Magnetization studies of amorphous antiferromagnetism in manganese phosphate glass

The magnetization of amorphous antiferromagnetic manganese phosphate glass has been studied as a function of manganese concentration, temperature, and magnetic field. The experimental results are interpreted using a two spin model of amorphous antiferromagnetism where the probability of a given exchange interaction is calculated using crystalline Mn 2P 2O 7 as a structural model.

Magnetic Structure of Manganese Pyrophosphate and Copper Pyrophosphate

The magnetic structures of antiferromagnetic manganese pyrophosphate and copper pyrophosphate have been determined by single crystal neutron diffraction techniques. There have been two previous determinations of the structure of manganese pyrophosphate. The discrepancy between these results is explained by postulating a crystallographic phase transition.

Magnetic Structure of Manganese Pyrophosphate, Mn2P2O7

The arrangement of the spins in antiferromagnetic manganese pyrophosphate at 4 °K has been determined by neutron diffraction from a powder specimen. The spins are in ferromagnetic sheets with the moment in each sheet aligned antiferromagnetically relative to its neighboring sheets.

Temperature dependence of the intensity of magnon sidebands in cubic antiferromagnetic manganese compounds

The anomalously high intensity and its temperature dependence of the optical absorption in MnO and MnS corresponding to the transitions 6 A 1 g → 4 T 1 g and 6 A 1 g → 4 T 2 g of Mn 2+ ion are interpreted as being due to sideband absorption associated with magnons. The pair approximation is used and the spin states of each ion pair are solved self-consistently. The calculated temperature dependence of the absorption intensity near and above the Néel temperature, relative to the intensity at 0°K, is in good agreement with the observation.

Temperature Dependence of the Intensity of Magnon Sidebands in Cubic Antiferromagnetic Manganese Compounds

Abstract The anomalously high intensity and its temperature dependence of the optical absorption in MnO and MnS corresponding to the transitions 6 A 1 g → 4 T 1 g and 6 A 1 g → 4 T 2 g of Mn 2+ ion are interpreted as being due to sideband absorption associated with magnons. The pair approximation is used and the spin states of each ion pair are solved self-consistently. The calculated temperature dependence of the absorption intensity near and above the Neel temperature, relative to the intensity at 0°K, is in good agreement with the observation.

Heat Capacity of Manganese Titanate from 30° to 300°K

The heat capacity of antiferromagnetic manganese titanate was measured between 31° and 300°K. The magnetic heat capacity of MnTiO3 was determined by subtracting the lattice heat capacity from the observed heat capacity. The lattice heat capacity of MnTiO3 may be represented by a sum of Debye and Einstein functions. The characteristic temperatures of MnTiO3 were estimated from the characteristic temperatures of isomorphous diamagnetic compounds. The entropy associated with the antiferromagnetic transition was calculated to be 3.51 cal deg−1, which is in good agreement with Rln6. Only 55% of the magnetic entropy is acquired by the Néel temperature at 62.3°K. The thermodynamic functions Cp, S° (H° − H0°) / T, and −(F° − H0°) / T of MnTiO3 in cal deg−1·mole−1 at 298.15°K are: 23.93, 25.08, 13.38, and 11.70.

Impurity-Induced Optical Fluorescence in MnF2

Cation impurity induced optical fluorescence in antiferromagnetic manganese difluoride at low temperatures, identifying fluorescence exciton lines by polarization and Zeeman experiments

Experimental investigation of two two-dimensional antiferromagnets with small anisotropy

Abstract The magnetic properties have been studied of two antiferromagnetic manganese compounds, K2MnF4 and Rb2MnF4, the crystal structure of these salts strongly suggesting the occurrence of largely isolated quadratic layers of magnetic atoms. The magnetic exchange for manganese being predominantly Heisenberg, the small anisotropy only arises from dipole-dipole interactions, as has been verified by measuring the antiferromagnetic threshold field at 4.2°K. The ordering temperature, as indicated by a steep fall in χ and a discontinuity in the derivative of χ⊥ is 45°K and 38.5°K for the two salts, respectively, and is located about 40% below the temperature where χ has its maximum. A value for J/k of - 4.1°K for K2MnF4 and - 3.3°K for Rb2MnF4 is obtained from various experimental data available. The corresponding ratio for kTN/J excellently agrees with predictions by Stanley and Kaplan for the two-dimensional Heisenberg ferromagnet.

Observation of a spin-wave sideband in the optical spectrum ofmnf2

Spin wave sideband in absorption spectrum at low temperatures for transition of manganese ion in antiferromagnetic manganese fluoride

Magnetic Properties of Manganese Telluride Single Crystals

The susceptibility and torque measurements of antiferromagnetic manganese telluride are made on the samples of single crystals. The spin orientation and structure are studied and discussed for the observed results of the field dependence and field cooling measurements. Some simple calculations are carried out, and some interpretations for the observed results are obtained on the basis of the assumption of the three-domain structure in the c -planes.

Low-Temperature Magnetic Properties of Dilute Mg-Mn, Al-Mn, Mg-Fe, and Al-Fe Alloys

Magnetic susceptibility measurements are reported on some dilute alloys of Mg-Mn and Al-Mn in the temperature range, room temperature -1.3\ifmmode^\circ\else\textdegree\fi{}K. Electron spin resonance (ESR) absorption has been observed in the magnesium alloy containing 0.6 at.% manganese and studied as a function of temperature. Room temperature magnetic susceptibility measurements and low temperature ESR experiments are reported for Mg-Fe and Al-Fe alloys. The concentration dependence of the Curie constant at high temperature suggests the presence of four unpaired electrons for the manganese atom dissolved in magnesium. Similar information concerning manganese dissolved in aluminum suggests one unpaired electron if a completely localized $d$ state is formed.The susceptibility of dilute Mg-Mn alloys shows departures from a Curie law, which could be interpreted as an increase in the spin state of the manganese ion in the region of the resistance minimum. This excess paramagnetism is discussed in terms of the possible mechanisms which could produce a resistance minimum and leads to the conclusion that if there is a ferromagnetic coupling between randomly distributed manganese pairs, the interaction mechanism operates over approximately 10 lattice spacings.The effective magneton number of Mn in the more dilute Mg-Mn alloys also increases with temperature at high temperatures. The susceptibility of the concentrated Mg-Mn alloy obeys a Curie law except in the region of the resistance maximum where both susceptibility and ESR data indicate an antiferromagnetic transition.The influence of the low-temperature transition, occurring in the magnesium alloy containing about 0.6 at.% manganese, on the electron spin resonance linewidth and magnetic field value has been measured as a function of temperature giving $g$ values of 2.01\ifmmode\pm\else\textpm\fi{}0.01 above 6\ifmmode^\circ\else\textdegree\fi{}K. The shift of the position of resonance field below 6\ifmmode^\circ\else\textdegree\fi{}K is consistent with antiferromagnetic behavior in Mg-Mn. The line shift is proportional to ${T}^{\ensuremath{-}1}$ in the antiferromagnetic region which would be consistent with a conduction electron superexchange mechanism for the antiferromagnetic manganese ion interaction. The linewidth is broadened in the region of the resistance minimum and attains a constant value as the temperature is lowered. This behavior is consistent with localized spin interactions, giving rise to larger averaged spin values in the resistance minimum region as suggested from the magnetic susceptibility studies of the more dilute alloys.

Magnetic susceptibilities and phase transitions of two antiferromagnetic manganese salts

The susceptibilities of single crystals of MnCl 2 ,4H 2 O and MnBr 2 .4H 2 O have been measured in the temperature region from 1°K to 300°K. Both crystals become antiferromagnetic in the liquid helium temperature region. Using the method of nuclear resonance absorption different transitions between antiferromagnetic states could be observed. The results are compared with the molecular field calculations of Gorter and Mrs. Van Peski-Tinbergen. The experimental data are in reasonable agreement with the theoretical calculations.

Magnetic susceptibilities and phase transitions of two antiferromagnetic manganese salts

The susceptibilities of single crystals of MnCl 2,4H 2O and MnBr 2.4H 2O have been measured in the temperature region from 1°K to 300°K. Both crystals become antiferromagnetic in the liquid helium temperature region. Using the method of nuclear resonance absorption different transitions between antiferromagnetic states could be observed. The results are compared with the molecular field calculations of Gorter and Mrs. Van Peski-Tinbergen. The experimental data are in reasonable agreement with the theoretical calculations.