Magnetic phase transitions and magnetoelastic coupling in 
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 Heisenberg antiferromagnets

al-Wahish, Amal; O’Neal, Kenneth; Lee, C.; Fan, Shiyu; Hughey, Kendall D.; Yokosuk, Michael O.; Clune, Amanda; Li, Z.; Schlueter, John A.; Manson, Jamie L.; Whangbo, Myung‐Hwan; Musfeldt, J. L.

doi:10.1103/physrevb.95.104437

Cited by 5 publications

(10 citation statements)

References 46 publications

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“…Figure summarizes the infrared responses of [Cu(pyz) 2 (2-HOpy) 2 ](PF 6 ) 2 and [Cu(pyz) 1.5 (4-HOpy) 2 ](ClO 4 ) 2 at 300 and 4.2 K. Although the molecular aspects of this class of material yield a number of vibrational modes below 2000 cm –1 , we find that, in general, they can be divided into two major groups: (i) those that behave anharmonically as a function of the temperature and (ii) those that reveal characteristics of hydrogen bonding . Through dynamics calculations and comparisons with chemically analogous materials (Figure S1), ,,, we assign the important modes. Given the fact that these materials are quite different in dimensionality and exchange strengththe PF 6 – complex has largely separated two-dimensional planes, whereas the ClO 4 – material is a nearly isotropic spin-ladder systemit is surprising to find that their temperature dependencies are rather similar.…”

Section: Resultsmentioning

confidence: 89%

“…With the addition of [Cu(pyz) 2 (2-HOpy) 2 ](PF 6 ) 2 and [Cu(pyz) 1.5 (4-HOpy) 2 ](ClO 4 ) 2 , the collection of copper-containing coordination polymers for which λ values have been evaluated across the magnetic quantum-phase transition is now broad enough to allow several interesting structure–property effects to emerge. Figure g summarizes the spin–phonon coupling constants for the pyz bend in this class of materials. − The overall trend is interesting. The pyz distortion in the spin ladder [Cu(pyz) 1.5 (4-HOpy) 2 ](ClO 4 ) 2 sports the strongest spin–phonon coupling (λ = 2.9 cm –1 ), whereas the one- and two-dimensional materials have slightly lower values ranging from 2.5 cm –1 in the chain compound to between 1.2 and 2 cm –1 in the various layered systems.…”

Section: Resultsmentioning

confidence: 94%

“…The data sets are normalized above the critical field, B C . (g) Comparison of the spin–phonon coupling constant of the out-of-plane pyz distortion as a function of the magnetic dimensionality in several well-known copper-containing coordination complexes. − …”

Section: Resultsmentioning

confidence: 99%

“…These findingstogether with similar magnetoinfrared work on other copper complexesare key to developing an unusual set of structure–property relationships involving both the magnetic dimensionality and spin–lattice interactions. While zero-dimensional (or “dot-like”) systems connected only by intermolecular hydrogen bonds display no spin–lattice coupling across this type of field-driven transition, coupling increases in the one-dimensional case, reaches a maximum in the ladder, and falls again in layered analogues. − The availability of the intermediate dimensionality system, [Cu(pyz) 1.5 (4-HOpy) 2 ](ClO 4 ) 2 , is crucial to unveiling this trend. Unlike the coupling constant trends in a magnetic field, there are no apparent correlations under pressure.…”

Section: Introductionmentioning

confidence: 99%

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Spin–Lattice Coupling Across the Magnetic Quantum-Phase Transition in Copper-Containing Coordination Polymers

et al. 2020

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We measured the infrared vibrational properties of two copper-containing coordination polymers, [Cu(pyz)2(2-HOpy)2](PF6)2 and [Cu(pyz)1.5(4-HOpy)2](ClO4)2, under different external stimuli in order to explore the microscopic aspects of spin–lattice coupling. While the temperature and pressure control hydrogen bonding, an applied field drives these materials from the antiferromagnetic → fully saturated state. Analysis of the pyrazine (pyz)-related vibrational modes across the magnetic quantum-phase transition provides a superb local probe of magnetoelastic coupling because the pyz ligand functions as the primary exchange pathway and is present in both systems. Strikingly, the PF6 – compound employs several pyz-related distortions in support of the magnetically driven transition, whereas the ClO4 – system requires only a single out-of-plane pyz bending mode. Bringing these findings together with magnetoinfrared spectra from other copper complexes reveals spin–lattice coupling across the magnetic quantum-phase transition as a function of the structural and magnetic dimensionality. Coupling is maximized in [Cu(pyz)1.5(4-HOpy)2](ClO4)2 because of its ladderlike character. Although spin–lattice interactions can also be explored under compression, differences in the local structure and dimensionality drive these materials to unique high-pressure phases. Symmetry analysis suggests that the high-pressure phase of the ClO4 – compound may be ferroelectric.

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Section: Resultsmentioning

confidence: 89%

Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spin–Lattice Coupling Across the Magnetic Quantum-Phase Transition in Copper-Containing Coordination Polymers

et al. 2020

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“…Counterion modes in other materials are also well localized and insensitive to magnetic field. 58 Although full magnetic saturation is not attained (because B C,theor. = 88 T and magneto-infrared spectroscopy at the National High Magnetic Field Laboratory is carried out with 35 T resistive magnets at this time), we find that ∫ |Δα|dω over the combined energy window tracks [M(B)] 2 very well (Figure 5f).…”

Section: Inorganic Chemistrymentioning

confidence: 99%

Structure–Property Relations in Multiferroic [(CH₃)₂NH₂]M(HCOO)₃(M= Mn, Co, Ni)

et al. 2018

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We bring together magnetization, infrared spectroscopy, and lattice dynamics calculations to uncover the magnetic field-temperature ( B- T) phase diagrams and vibrational properties of the [(CH)NH] M(HCOO) ( M = Mn, Co, Ni) family of multiferroics. While the magnetically driven transition to the fully saturated state in [(CH)NH]Mn(HCOO) takes place at 15.3 T, substitution with Ni or Co drives the critical fields up toward 100 T, an unexpectedly high energy scale for these compounds. Analysis of the infrared spectrum of the Mn and Ni compounds across T reveals doublet splitting of the formate bending mode which functions as an order parameter of the ferroelectric transition. By contrast, [(CH)NH]Co(HCOO) reveals a surprising framework rigidity across the order-disorder transition due to modest distortions around the Co centers. The transition to the ferroelectric state is thus driven by the dimethylammonium cation freezing and the resulting hydrogen bonding. Under applied field, the Mn (and most likely, the Ni) compounds engage the formate bending mode to facilitate the transition to their fully saturated magnetic states, whereas the Co complex adopts a different mechanism involving formate stretching distortions to lower the overall magnetic energy. Similar structure-property relations involving substitution of transition-metal centers and control of the flexible molecular architecture are likely to exist in other molecule-based multiferroics.

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High-Field Magnetoelectric and Spin-Phonon Coupling in Multiferroic (NH₄)₂[FeCl₅·(H₂O)]

et al. 2022

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We combine high field polarization, magneto-infrared spectroscopy, and lattice dynamics calculations with prior magnetization to explore the properties of (NH4)2[FeCl5·(H2O)]a type II molecular multiferroic in which the mixing between charge, structure, and magnetism is controlled by intermolecular hydrogen and halogen bonds. Electric polarization is sensitive to the series of field-induced spin reorientations, increasing linearly with the field and reaching a maximum before collapsing to zero across the quasi-collinear to collinear-sinusoidal reorientation due to the restoration of inversion symmetry. Magnetoelectric coupling is on the order of 1.2 ps/m for the P∥c, H∥c configuration between 5 and 25 T at 1.5 K. In this range, the coupling takes place via an orbital hybridization mechanism. Other forms of mixing are active in (NH4)2[FeCl5·(H2O)] as well. Magneto-infrared spectroscopy reveals that all of the vibrational modes below 600 cm–1 are sensitive to the field-induced transition to the fully saturated magnetic state at 30 T. We analyze these local lattice distortions and use frequency shifts to extract spin-phonon coupling constants for the Fe–O stretch, Fe–OH2 rock, and NH4 + libration. Inspection also reveals subtle symmetry breaking of the ammonium counterions across the ferroelectric transition. The coexistence of such varied mixing processes in a platform with intermolecular hydrogen- and halogen-bonding opens the door to greater understanding of multiferroics and magnetoelectrics governed by through-space interactions.

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Magnetic phase transitions and magnetoelastic coupling in S=12 Heisenberg antiferromagnets

Cited by 5 publications

References 46 publications

Spin–Lattice Coupling Across the Magnetic Quantum-Phase Transition in Copper-Containing Coordination Polymers

Spin–Lattice Coupling Across the Magnetic Quantum-Phase Transition in Copper-Containing Coordination Polymers

Structure–Property Relations in Multiferroic [(CH₃)₂NH₂]M(HCOO)₃(M= Mn, Co, Ni)

High-Field Magnetoelectric and Spin-Phonon Coupling in Multiferroic (NH₄)₂[FeCl₅·(H₂O)]

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Magnetic phase transitions and magnetoelastic coupling in S=12 Heisenberg antiferromagnets

Cited by 5 publications

References 46 publications

Spin–Lattice Coupling Across the Magnetic Quantum-Phase Transition in Copper-Containing Coordination Polymers

Spin–Lattice Coupling Across the Magnetic Quantum-Phase Transition in Copper-Containing Coordination Polymers

Structure–Property Relations in Multiferroic [(CH3)2NH2]M(HCOO)3(M= Mn, Co, Ni)

High-Field Magnetoelectric and Spin-Phonon Coupling in Multiferroic (NH4)2[FeCl5·(H2O)]

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Product

Resources

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Structure–Property Relations in Multiferroic [(CH₃)₂NH₂]M(HCOO)₃(M= Mn, Co, Ni)

High-Field Magnetoelectric and Spin-Phonon Coupling in Multiferroic (NH₄)₂[FeCl₅·(H₂O)]