Organic ferroelectric croconic acid: a concise survey from bulk single crystals to thin films

Mohapatra, Sambit; Cherifi‐Hertel, Salia; Kumar, Kuppusamy Senthil; Schmerber, G.; Arabski, J.; Gobaut, Benoît; Weber, W.; Bowen, M.; Costa, V. Da; Boukari, S.

doi:10.1039/d1tc05310h

Cited by 7 publications

(5 citation statements)

References 144 publications

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“…On the other hand, Croconic acid (CA) is emerging as a potential ferroelectric material due to its organic nature and the highest above-room-temperature saturation polarization value. [19][20][21][22] Such a high polarization value at and above room-temperature certainly advocates for its application in spintronics. [23,24] With much lower stiffness constant of organic materials compared to magnetic metals, its application as the ferroelectric component in a composite multiferroic can lead to the design of purely magnetoelectric-based artificial multiferroic systems.…”

Section: Introductionmentioning

confidence: 99%

Polarization Vector Canting in Croconic Acid Ferroelectric Nanoscopic Regions

Mohapatra,

Weber,

Gobaut

et al. 2024

Adv Materials Technologies

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Croconic acid is reported to be the organic ferroelectric with the highest above‐room‐temperature saturation polarization in its crystal form, at a value on par with that of commonly used inorganic ferroelectrics. Owing to its organic nature, high polarization value, and small coercive field, Croconic acid is considered as a potential candidate in energy‐efficient and environmentally benign composite multiferroic heterostructures. However, understanding the magnetoelectric mechanism at the ferroelectric/ferromagnetic interface in these structures requires a detailed understanding of the orientation of the polarization vector in its thin film form. To maximize the magnetoelectric effect, the polarization vector should point out of the film plane, yet the polarization in ultra‐thin Croconic acid films is predicted to lie in the film plane. Nevertheless, polycrystalline films show some promise in this direction. In this article, by combining in situ piezoreponse force microscopy imaging with nanoscopic polarization reversal spectroscopy, the authors qualitatively analyze the polarization switching and its orientation in polycrystalline Croconic acid films and show that it is canted with respect to the film plane, with a component along the out‐of‐plane direction.

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Section: Introductionmentioning

confidence: 99%

Polarization Vector Canting in Croconic Acid Ferroelectric Nanoscopic Regions

Mohapatra,

Weber,

Gobaut

et al. 2024

Adv Materials Technologies

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“…Molecular materials that show switching of a physical property-for example, magnetic [1][2][3][4][5][6][7][8][9][10][11][12] or electric [13][14][15][16][17] -accompanied with hysteresis are candidates desirable for applications. Several classes of magnetic-molecular systems such as organic radicals, [18][19][20] single-molecule magnets (SMMs), 3,[21][22][23] and spin-crossover (SCO) complexes [24][25][26][27][28][29][30][31] are known to show bistable switching characteristic.…”

Section: Introductionmentioning

confidence: 99%

Substituent-dependent spin-state switching in isomeric iron(II) complexes: from bi-stable spin-state switching with T1/2 centred at room temperature to trapped high-spin state

Kuppusamy,

Mizuno,

Spieker

et al. 2024

Preprint

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Spin-state switching in iron(II) complexes composed of ligands featuring moderate ligand-field strength—for example, 2,6-bi(1H-pyrazol-1-yl)pyridine (BPP)—is dependent on many factors—examples include lattice solvent, counter anion, and substituent. Herein, we show that spin-state switching in isomeric iron(II) complexes (1·CH3CN and 2) composed of tridentate all nitrogen coordinating ligands—ethyl 2,6-bis(1H-pyrazol-1-yl)isonicotinate (BPP-COOEt, L1) and (2,6-di(1H-pyrazol-1-yl)pyridin-4-yl)methylacetate (BPP-CH2OCOMe, L2)—is controlled by the nature of substituent at the fourth position of the pyridine ring of the BPP skeleton. Complex 1·CH3CN, crystallized with acetonitrile solvent, undergoes abrupt and hysteretic spin-state switching, hence bistable switching, with a thermal hysteresis width (ΔT1/2) of 44 K and switching temperature (T1/2) = 298 K in the first cycle. Conversely, the isomeric counterpart of 1·CH3CN—complex 2—crystallized with no lattice solvent; the complex was trapped in the high-spin (HS) state upon cooling from 300 K. Molecular structures of the LS and HS forms of complex 1·CH3CN revealed that spin-state switching induces a pronounced angular distortion, creating an energy barrier separating the LS and HS states. Traversing the barrier requires substantial molecular rearrangement in the presence of constraints imposed by the crystal lattice, rendering the spin-state switching of 1·CH3CN hysteretic in the solid-state. The observation of bistable spin-state switching with T1/2 centred at room temperature for 1·CH3CN as well as the attribution of pronounced angular distortion and conformational variation of the COOEt substituent as causes behind the observed hysteretic spin-state switching indicates that technologically relevant spin-state switching profiles based on mononuclear iron(II) complexes can be obtained.

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“…Molecular materials that show switching of a physical property -for example, magnetic [1][2][3][4][5][6][7][8][9][10][11][12] or electric [13][14][15][16][17] -accompanied by hysteresis are candidates desirable for applications. Several classes of magnetic-molecular systems such as organic radicals, [18][19][20] single-molecule magnets (SMMs), 3,[21][22][23] and spincrossover (SCO) complexes [24][25][26][27][28][29][30][31] are known to show bistable switching characteristics.…”

Section: Introductionmentioning

confidence: 99%

Lattice solvent- and substituent-dependent spin-crossover in isomeric iron(ii) complexes

Kuppusamy,

Mizuno,

Kämmerer

et al. 2024

Dalton Trans.

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Organic ferroelectric croconic acid: a concise survey from bulk single crystals to thin films

Abstract: Owing to prospective energy-efficient and environmentally benign applications, organic ferroelectric materials are useful and necessary alternative to inorganic ferroelectrics. Although the first discovered ferroelectric, Rochelle salt, was a salt of...

Cited by 7 publications

References 144 publications

Polarization Vector Canting in Croconic Acid Ferroelectric Nanoscopic Regions

Polarization Vector Canting in Croconic Acid Ferroelectric Nanoscopic Regions

Substituent-dependent spin-state switching in isomeric iron(II) complexes: from bi-stable spin-state switching with T1/2 centred at room temperature to trapped high-spin state

Lattice solvent- and substituent-dependent spin-crossover in isomeric iron(ii) complexes

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