Experimental investigation of two two-dimensional antiferromagnets with small anisotropy

Breed, D. J.

doi:10.1016/0031-8914(67)90103-6

Cited by 145 publications

(16 citation statements)

References 12 publications

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“…The anisotropy parameter a was previously found to be 0.04 [1]. For a quadratic Heisenberg antiferromagnet e(a) = 0.63 when a = 0.04 [13]. We conclude that the values for J/k resulting from the above analyses are in good agreement with J/k = -0.25 (1) K, found previously from the susceptibility and magnetization measurements.…”

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confidence: 80%

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1,2,4-Triazole Complexes XIV

Engelfriet

Groeneveld

Nap

1980

Zeitschrift Für Naturforschung A

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Heat capacity measurements on Mn(trz)2(NCS)2 in the range 1 -90 K are reported. A ?.-anomaly is found at Tc -3.292(6) K. From a comparison of the high-temperature specific heat to the predictions from series expansions the intralayer exchange constant is found to be J/k = 0.245(5) K. From the total magnetic energy involved in the transition the value J/k = -0.254(8) K is calculated. These results compare favourably with previous data from susceptibility measurements.From very recent X-ray diffraction experiments on a single crystal the space group is found to be Pbcn instead of Aba2, as was reported previously.In a recent paper [1] it was shown that the magnetic properties of Mn(l,2,4-triazole)2(NCS)2 are in good agreement with the predictions for a 2-where M is a 3d-metal, which exhibits 2-d magnetic properties [1,3,4] as is to be expected from the layered crystal structure [5,6].Very recent X-ray diffraction experiments on a single crystal of Mn(trz)2(NCS)2 indicated the space group to be Pbcn instead of Aba2, as we reported previously [1]. The axes were found asa = 8.003 (3), b -10.086(4), and c= 16.256(4) Ä. Thus the title compound is isomorphous to its Zn analogue, which also has a layered structure, very similar to that of the Co and Fe complexes [5]. This result does not affect the conclusions from the magnetic measurements. Both in Aba2 and Pbcn Mn is positioned on a two-fold axis, which must necessarily be primed. When we assume that below Tc the nuclear frame can still be described in Pbcn, the magnetic space group will be Pbcn'. From magnetic susceptibility and magnetization measurements on single crystals the intralayer exchange constant was found as J/k =0.25(1) K, while preliminary results from heat capacity measurements indicated the slightly lower value -0.23(1) K [1].In this note we present the heat capacity data on a powdered sample of Mn(trz) 2 (NCS)2. The measurements were performed in the temperature range 1-90 K, using conventional heat-pulse techniques ui Figure 1 shows the measured specific heat. From the peak the ordering temperature is found as Tc = 3.292 (6) K. Between 6 and 10 K the data could be well described by the equationwhere CL and CM denote the lattice and magnetic contributions, respectively, to the specific heat. A good fit to Eq. (1) was obtained with a = 4.2(1) X 10-3 J/K4 mole and 6 = 115(2) JK/mole.From the value of the coefficient b the exchange constant is calculated as | J\/k = 0.26(1) K, using the Heisenberg model prediction:0340-4811 I 80 / 1200-1387 $ 01.00/0. -Please order a reprint rather than making your own copy.

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“…The magnetic energy is EQ = 56(2) J/mole, of which 35% is gained below Tc. energy the value | J\ /k = -0.254(8) K is calculated using the formula given by spin-wave theory [13]:…”

mentioning

confidence: 99%

1,2,4-Triazole Complexes XIV

Engelfriet

Groeneveld

Nap

1980

Zeitschrift Für Naturforschung A

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“…Among the low dimensional magnets with isotropic high temperature susceptibility are: MnF 2 [29], K 2 NiF 4 [31,33], Rb 2 NiF 4 [33], Rb 2 MnF 4 [30] and K 2 MnF 4 [32]. The observed excitation gaps of these materials are: 12.6, 27.5, 49.6, 7.28 and 7.4 K [34].…”

Section: Article In Pressmentioning

confidence: 99%

“…In axial crystals pure spin magnetism and therefore absence of single particle anisotropy is proven by the isotropy of the high temperature susceptibility [29][30][31][32][33]. Among the low dimensional magnets with isotropic high temperature susceptibility are: MnF 2 [29], K 2 NiF 4 [31,33], Rb 2 NiF 4 [33], Rb 2 MnF 4 [30] and K 2 MnF 4 [32].…”

Section: Article In Pressmentioning

confidence: 99%

Critical magnetic behaviour in one and two dimensions

Köbler

Hoser

2007

Journal of Magnetism and Magnetic Materials

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“…Considering the spin reduction as a function of a as calculated by Colpa et al [44] we obtain for KMnF 4 S(a)/S = 0.10. The quantity e(a) is almost independent of a [45], so we use the value e(0) = 0.632 given by Keffer and Breed [30,46]. With the experimental values of the perpendicular susceptibilities x b (0) and x c (0) ( see above) we obtain from (7) the anisotropy parameters a = 0.65 and a = 1.40, and hence the in-plane anisotropy D x //c= 1.7 (3) K and out-of-plane anisotropy DJk = 3.5 K, respectively.…”

Section: Magnetic Study Of the 2d Antiferromagnet Kmnfmentioning

confidence: 99%

Magnetism of Alkalitetrafluoromanganates (III) AMnF₄ (A = K, Rb, Cs): Neutron Diffraction, Mössbauer and Magnetization Investigations

Molinier

Frommen

Massa

et al. 1993

Zeitschrift Für Naturforschung A

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The magnetic properties of the d 4 Jahn-Teller systems A'Mn m F 4 with layered structures were investigated. Neutron diffraction on powders of KMnF 4 and RbMnF 4 revealed different antiferromagnetic spin arrangements below T N = 4.5 K and 2.3 K, respectively: for KMnF 4 canted antiparallel along a and b, for RbMnF 4 parallel along a and antiparallel along b, in both cases parallel along c, the stacking direction of layers. Mössbauer investigations on 57 Fe doped KMnF 4 confirmed a spin orientation approximately within the layer plane. A discussion is given of the contributions to the magnetic hyperfine field and the Mössbauer linewidth in quasi-two-dimensional antiferromagnets with Ising anisotropy due to thermal excitation of domain wall dynamics (solitons). The experimental data seem to confirm the predicted exponential temperature dependence of the linewidth. From magnetization measurements on powders and a single crystal of KMnF 4 the 2-d exchange energy and the out-of-plane and in-plane anisotropies could be extracted. In addition, from susceptibility measurements the exchange energies of NaMnF 4 , RbMnF 4 and CsMnF 4 were calculated. A linear dependence of these exchange energies (positive for ferromagnetic CsMnF 4 , negative for the other AMnF 4 compounds) on the cos 2 of the Mn-F-Mn bridge angle is observed and compared with the behaviour of the AFeF 4 compounds which is also linear but with reverse sign of the slope. The specific superexchange mechanisms active in Jahn-Teller systems with antiferrodistortively ordered layers are suggested to be responsible for these findings.

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Experimental investigation of two two-dimensional antiferromagnets with small anisotropy

Cited by 145 publications

References 12 publications

1,2,4-Triazole Complexes XIV

1,2,4-Triazole Complexes XIV

Critical magnetic behaviour in one and two dimensions

Magnetism of Alkalitetrafluoromanganates (III) AMnF₄ (A = K, Rb, Cs): Neutron Diffraction, Mössbauer and Magnetization Investigations

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Experimental investigation of two two-dimensional antiferromagnets with small anisotropy

Cited by 145 publications

References 12 publications

1,2,4-Triazole Complexes XIV

1,2,4-Triazole Complexes XIV

Critical magnetic behaviour in one and two dimensions

Magnetism of Alkalitetrafluoromanganates (III) AMnF4 (A = K, Rb, Cs): Neutron Diffraction, Mössbauer and Magnetization Investigations

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Magnetism of Alkalitetrafluoromanganates (III) AMnF₄ (A = K, Rb, Cs): Neutron Diffraction, Mössbauer and Magnetization Investigations