Experimentally determining the exchange parameters of quasi-two-dimensional Heisenberg magnets

Goddard, Paul; Singleton, John; Sengupta, Pinaki; McDonald, R. D.; Lancaster, Tom; Blundell, Stephen J.; Pratt, F. L.; Cox, Susan; Harrison, N.; Manson, Jamie L.; Southerland, Heather I.; Schlueter, John A.

doi:10.1088/1367-2630/10/8/083025

Cited by 120 publications

(230 citation statements)

References 35 publications

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“…25,26 The linear character of M (B) between B SF and B Sat is in line with expectations for a three-dimensional system. 7 In our analysis of the magnetization and exchange interactions, we employ the experimentally-determined saturation field (B Sat =15.3 T) and the spin Hamiltonian…”

Section: Resultsmentioning

confidence: 99%

“…Examples include the classic spin flop, 1-6 magnetic saturation transitions, [7][8][9] and those with a sequence of metamagnetic, helical, and nano-pantograph spin states. [10][11][12] The emergent class of tunable multiferroics with chemical formula [(CH 3 ) 2 NH 2 ]M (HCOO) 3 (M = Mn 2+ , Fe 2+ , Ni 2+ , Co 2+ ) provides a number of exciting opportunities in this regard.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic field-temperature phase diagram of multiferroic [(CH3)2NH2]Mn(HCOO)3<

et al. 2017

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We combined pulsed field magnetization and first principles spin density calculations to reveal the magnetic field-temperature phase diagram and spin state character in multiferroic [(CH3)2NH2]Mn(HCOO)3. Despite similarities with the rare earth manganites, the phase diagram is analogous to other Mn-based quantum magnets with a 0.31 T spin flop, a 15.3 T transition to the fully polarized state, and short range correlations that persist above the ordering temperature. The experimentally accessible saturation field opens the door to exploration of the high field phase.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Magnetic field-temperature phase diagram of multiferroic [(CH3)2NH2]Mn(HCOO)3<

et al. 2017

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“…The main variation in the room temperature structure on moving across this family is in the tilt angle of the pyrazines. For the materials with octahedral anions, this angle is close to 90 • , but is significantly smaller for the tetrahedral-anion materials 11 . More differences appear on cooling.…”

mentioning

confidence: 85%

“…The twist angle is that between the N· · · N axis of the pyrazine molecules and the copper-copper pathways in the two-dimensional planes. The last line shows data measured at 15 K for the related material [Cu(HF2)(pyz)2]SbF6 [11], which is compared to 1-4 in later discussions.…”

Section: Fig 1 (Color Online)mentioning

confidence: 99%

Control of the third dimension in copper-based square-lattice antiferromagnets

et al. 2016

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Using a mixed-ligand synthetic scheme, we create a family of quasi-two-dimensional antiferromagnets, namely, [Cu(HF2)(pyz)2]ClO4 [pyz = pyrazine], [CuL2(pyz)2](ClO4)2 [L = pyO = pyridine-N-oxide and 4-phpyO = 4-phenylpyridine-N-oxide. These materials are shown to possess equivalent two-dimensional [Cu(pyz)2] 2+ nearly square layers, but exhibit interlayer spacings that vary from 6.5713Å to 16.777Å, as dictated by the axial ligands. We present the structural and magnetic properties of this family as determined via x-ray diffraction, electron-spin resonance, pulsed-and quasistatic-field magnetometry and muon-spin rotation, and compare them to those of the prototypical two-dimensional magnetic polymer Cu(pyz)2(ClO4)2. We find that, within the limits of the experimental error, the two-dimensional, intralayer exchange coupling in our family of materials remains largely unaffected by the axial ligand substitution, while the observed magnetic ordering temperature (1.91 K for the material with the HF2 axial ligand, 1.70 K for the pyO and 1.63 K for the 4-phpyO) decreases slowly with increasing layer separation. Despite the structural motifs common to this family and Cu(pyz)2(ClO4)2, the latter has significantly stronger two-dimensional exchange interactions and hence a higher ordering temperature. We discuss these results, as well as the mechanisms that might drive the long-range order in these materials, in terms of departures from the ideal S = 1/2 two-dimensional square-lattice Heisenberg antiferromagnet. In particular, we find that both spin exchange anisotropy in the intralayer interaction and interlayer couplings (exchange, dipolar, or both) are needed to account for the observed ordering temperatures, with the intralayer anisotropy becoming more important as the layers are pulled further apart.

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“…However the magnetism is very two-dimensional as a result of very weak couplings through Cu-FHF-Cu bonds 25 due to limited overlap between the fluorine p z orbital and the magnetic orbital of Cu(II), d x 2 −y 2 , lying in the [Cu(pyz) 2 ] 2+ planes. 26 The last three examples above contain axial ClO − 4 , BF − 4 or pyO ligands and the 2D layers stack in a staggered fashion.…”

Section: Introductionmentioning

confidence: 99%

Antiferromagnetism in a Family of S = 1 Square Lattice Coordination Polymers NiX₂(pyz)₂ (X = Cl, Br, I, NCS; pyz = Pyrazine)

et al. 2016

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Magnetism in a family of S = 1 square lattice antiferromagnets NiX 2 (pyz) 2 (X = Cl, Br, I, NCS; pyz = pyrazine) The crystal structures of NiX2(pyz)2 (X = Cl (1), Br (2), I (3) and NCS (4)) were determined at 298 K by synchrotron X-ray powder diffraction. All four compounds consist of two-dimensional (2D) square arrays self-assembled from octahedral NiN4X2 units that are bridged by pyz ligands. The 2D layered motifs displayed by 1-4 are relevant to bifluoride-bridged [Ni(HF2)(pyz)2]ZF6 (Z = P, Sb) which also possess the same 2D layers. In contrast, terminal X ligands occupy axial positions in 1-4 and cause a staggering of adjacent layers. Long-range antiferromagnetic order occurs below 1.5 (Cl), 1.9 (Br and NCS) and 2.5 K (I) as determined by heat capacity and muon-spin relaxation. The single-ion anisotropy and g factor of 2, 3 and 4 are measured by electron spin resonance where no zero-field splitting was found. The magnetism of 1-4 crosses a spectrum from quasi-two-dimensional to three-dimensional antiferromagnetism. An excellent agreement was found between the pulsedfield magnetization, magnetic susceptibility and TN of 2 and 4. Magnetization curves for 2 and 4 calculated by quantum Monte Carlo simulation also show excellent agreement with the pulsed-field data. 3 is characterized as a three-dimensional antiferromagnet with the interlayer interaction (J ⊥ ) slightly stronger than the interaction within the two-dimensional [Ni(pyz)2] 2+ square planes (Jpyz).

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Experimentally determining the exchange parameters of quasi-two-dimensional Heisenberg magnets

Cited by 120 publications

References 35 publications

Magnetic field-temperature phase diagram of multiferroic [(CH3)2NH2]Mn(HCOO)3<

Magnetic field-temperature phase diagram of multiferroic [(CH3)2NH2]Mn(HCOO)3<

Control of the third dimension in copper-based square-lattice antiferromagnets

Antiferromagnetism in a Family of S = 1 Square Lattice Coordination Polymers NiX₂(pyz)₂ (X = Cl, Br, I, NCS; pyz = Pyrazine)

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Experimentally determining the exchange parameters of quasi-two-dimensional Heisenberg magnets

Cited by 120 publications

References 35 publications

Magnetic field-temperature phase diagram of multiferroic [(CH3)2NH2]Mn(HCOO)3<

Magnetic field-temperature phase diagram of multiferroic [(CH3)2NH2]Mn(HCOO)3<

Control of the third dimension in copper-based square-lattice antiferromagnets

Antiferromagnetism in a Family of S = 1 Square Lattice Coordination Polymers NiX2(pyz)2 (X = Cl, Br, I, NCS; pyz = Pyrazine)

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Product

Resources

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Antiferromagnetism in a Family of S = 1 Square Lattice Coordination Polymers NiX₂(pyz)₂ (X = Cl, Br, I, NCS; pyz = Pyrazine)