Global Phase Diagram of the Magnetic Field-Induced Organic Superconductors λ-(BETS)2FexGa1-xCl4

Uji, S.; Terashima, Taichi; Terakura, C.; Yakabe, Taro; Terai, Yoshikazu; Yasuzuka, Syuma; Imanaka, Y.; Tokumoto, M.; Kobayashi, Akiko; Sakai, Fuminori; Tanaka, Hisashi; Kobayashi, Hayao; Balicas, Luis; Brooks, J. S.

doi:10.1143/jpsj.72.369

Cited by 54 publications

(33 citation statements)

References 18 publications

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“…In the latter case, a ''-d'' interaction is introduced between the donor conduction electrons and the localized d electrons. A dramatic example of the effects of the -d interaction includes the observation of magnetic field induced superconductivity [15][16][17] and evidence for the Fulde-Ferrell-Larkin-Ovchinnikov ground state [18] in -BETS 2 FeCl 4 .…”

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confidence: 99%

Antiferromagneticd-Electron Exchange via a Spin-Singletπ-Electron Ground State in an Organic Conductor

et al. 2008

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Electron spin resonance reveals the spin behavior of conduction (pi) and localized (d) electrons in beta-(BDA-TTP)2MCl4 (M=Fe, Ga). Both the Ga3+(S=0) and Fe3+(S=5/2) compounds exhibit a metal-insulator transition at 113 K with the simultaneous formation of a spin-singlet ground state in the pi electron system of the donor molecules. The behavior is consistent with charge ordering in beta-(BDA-TTP)2MCl4 at the metal-insulator transition. At 5 K, the Fe3+ compound orders antiferromagnetically, even though the pi electrons, which normally would facilitate magnetic exchange, are localized nonmagnetic singlets.

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confidence: 99%

Antiferromagneticd-Electron Exchange via a Spin-Singletπ-Electron Ground State in an Organic Conductor

et al. 2008

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“…From a simple spin-spitting argument, ∆F = gm ef f /4m 0 B J , for x=1, where ∆F = 128 T, m ef f /m 0 = 4, and g = 2, the exchange field is B J = 32 T. Remarkably, B J depended linearly on the Fe concentration, and extrapolated to zero for x = 0. The connection between the λ-(BETS) 2 GaCl 4 and the λ-(BETS) 2 FeCl 4 , and how the exchange field could be "tuned" from zero to its maximum value was conclusively demonstrated in a systematic investigation [13] of λ-(BETS) 2 Fe x Ga 1−x Cl 4 , the results of which are shown in Fig. 3.…”

Section: At Higher Magnetic Fields Field Induced Superconductivity mentioning

confidence: 82%

“…It is noteworthy that from the Dingle analysis, the mean free path in λ-(BETS) 2 FeCl 4 can be as large as 100 nm, or about an order of magnitude larger than the coherence length in λ-(BETS) 2 GaCl 4 (of order 10 nm), and hence the system is in the clean limit. [13] Although the comparison between experiment and theory is compelling, further work is needed to demonstrate the FFLO state convincingly in these materials. This is in part due to the quasitwo dimensional nature of the system, which complicates the more robust theoretical result obtained from a quasi-one dimensional approach to the FFLO ground state.…”

Section: At Higher Magnetic Fields Field Induced Superconductivity mentioning

confidence: 99%

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High field alloy, thermoelectric, and mm wave studies of the field induced superconducting state in l-(BETS)2Fe xGa1-xCl4

Brooks¹,

Uji²,

Choi³

et al. 2003

Braz. J. Phys.

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Alloy studies in the π -d organic conductor λ-(BETS) 2 Fe x Ga 1−x Cl 4 have given new insight into the nature of field induced superconductivity (FISC), since the mechanism of the FISC involves cancellation of the π − d exchange field by the external field. Alloying on the Fe x Ga 1−x site allows tuning of the exchange field, thereby influencing the FISC phase boundary. A brief review of the low temperature phases are given, and new high magnetic field thermoelectric and mm wave results that probe the low temperature ground state are presented.The discovery of magnetic field induced superconductivity in λ-(BETS) 2 FeCl 4 [1] (BETS= bis(ethylenedithio)tetraselenafulvalene) has drawn attention to the π−d electron spin exchange mechanisms [2] in molecular systems where magnetic order in the d electron system strongly influences the behavior of the conducting π electron system. The magnetic field dependent phase diagram of the λ-(BETS) 2 FeCl 4 material is shown in Fig. 1. For H =0, and below the metal-insulator transition temperature (T M I = 8.3K), λ-(BETS) 2 FeCl 4 enters a highly insulating antiferromagnetic (AFI) phase [3]. Below T M I , a spin-flop transition to a canted antiferromagnetic (CAF) phase occurs near 1 T, and above 11 T, a paramagnetic metallic (PM) phase appears.At higher magnetic fields , field induced superconductivity (FISC) is stabilized in λ-(BETS) 2 FeCl 4 below 5 K between 18 and 45 T [1,4]. The FISC state involves the cancellation of the exchange field B J by the external magnetic field B ext , i.e. the effective internal field in the conduction electron layer is B ef f = B ext − |B J | ( i.e. the JaccarinoPeter or J-P effect [5,6], where for the π − d discussed here, B J is negative.). Although the AFI-PM transition is nearly independent of field direction, the PM-FISC transition requires careful alignment of the field in the a-c molecular planes to avoid orbital dissipation in the superconducting phase. Recently a similar FISC state has been reported in κ-(BETS) 2 FeBr 4 by Tanatar and co-workers. [11] The more general λ-(BETS) 2 Fe x Ga 1−x Br y Cl 4−y class of organic conductors, with localized magnetic moments at the anion sites, and conduction electrons in the molecularcation layers, exhibit competition between magnetic, metallic, insulating, and superconducting ground states. This is exemplified in Fig. 2a and 2 When the FISC was first discovered, it was tempting to anticipate that in order to exist at high fields, the superconducting state might arise from unconventional mechanisms such as triplet pairing. (See Lebed and Yamaji [10] for a recent theoretical treatment of possible low-D, high field, ground states.) However, the subsequent discovery that the superconducting phase was re-entrant at high magnetic fields, and that it had a "symmetry" around 32 T at the center of the FISC state, suggested that the Jaccarino-Peter mechanism should be seriously considered. Here, in simple terms, an external field of 32 T would cancel the corresponding exchange field J of the same order....

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“…Assembled hetero-molecular systems such as organic-inorganic hybrid system have the possibility to undergo significant concert phenomena as a whole system through the hetero-molecular interaction between the constituent elements. In the case of conjugated phenomena coupled with transport and magnetic properties, for example, a metallic organic conductor coexisting with ferromagnetism for (BEDT-TTF) 3 [Mn(II)Cr(III)(C 2 O 4 ) 3 ] (BEDT-TTF = 4,5-bis(ethylenedithio)tetrathiafulvalene) [1], a field-induced superconductivity for λ-(BETS) 2 FeCl 4 (BETS = 4,5-bis(ethylenedithio) tetraselenafulvalene) [2,3], or the competition of superconducting phase and insulating antiferromagnetic phase for λ-(BETS) 2 Ga 1-x Fe x Cl 4 [4] have been reported. In the case of phenomena coupled with optical and magnetic properties, the light induced excited spin state trapping (LIESST) in spin-crossover complexes [5,6,7], or the photo-induced magnetism in transition metal cyanides [8,9,10,11,12,13] have been reported.…”

Section: Introductionmentioning

confidence: 99%

Progress of Multi Functional Properties of Organic-Inorganic Hybrid System, A[FeIIFeIIIX3] (A = (n-CnH2n+1)4N, Spiropyran; X = C2O2S2, C2OS3, C2O3S)

et al. 2010

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In the case of mixed-valence systems whose spin states are situated in the spin crossover region, new types of conjugated phenomena coupled with spin and charge are expected. From this viewpoint, we have investigated the multifunctional properties coupled with spin, charge and photon for the organic-inorganic hybrid system, A[FeIIFeIIIX3](A = (n-CnH2n+1)4N, spiropyran; X = dto(C2O2S2), tto(C2OS3), mto(C2O3S)). A[FeIIFeIII(dto)3] and A[FeIIFeIII(tto)3] undergo the ferromagnetic phase transitions, while A[FeIIFeIII(mto)3] undergoes a ferrimagnetic transition. In (n-CnH2n+1)4N [FeIIFeIII(dto)3](n = 3,4), a new type of phase transition called charge transfer phase transition (CTPT) takes place around 120 K, where the thermally induced charge transfer between FeII and FeIII occurs reversibly. At the CTPT, the iron valence state dynamically fluctuated with a frequency of about 0.1 MHz, which was confirmed by means of muon spin relaxation. The charge transfer phase transition and the ferromagnetic transition for (n-CnH2n+1)4N[FeIIFeIII(dto)3] remarkably depend on the size of intercalated cation. In the case of (SP)[FeIIFeIII(dto)3](SP = spiropyran), the photoinduced isomerization of SP under UV irradiation induces the charge transfer phase transition in the [FeIIFeIII(dto)3] layer and the remarkable change of the ferromagnetic transition temperature. In the case of (n-CnH2n+1)4N[FeIIFeIII(mto)3](mto = C2O3S), a rapid spin equilibrium between the high-spin state (S = 5/2) and the low-spin state (S = 1/2) at the FeIIIO3S3 site takes place in a wide temperature range, which induces the valence fluctuation of the FeS3O3 and FeO6 sites through the ferromagnetic coupling between the low spin state (S = 1/2) of the FeIIIS3O3 site and the high spin state (S = 2) of the FeIIO6 site.

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Global Phase Diagram of the Magnetic Field-Induced Organic Superconductors λ-(BETS)₂Fe_xGa_1-xCl₄

Cited by 54 publications

References 18 publications

Antiferromagneticd-Electron Exchange via a Spin-Singletπ-Electron Ground State in an Organic Conductor

Antiferromagneticd-Electron Exchange via a Spin-Singletπ-Electron Ground State in an Organic Conductor

High field alloy, thermoelectric, and mm wave studies of the field induced superconducting state in l-(BETS)2Fe xGa1-xCl4

Progress of Multi Functional Properties of Organic-Inorganic Hybrid System, A[FeIIFeIIIX3] (A = (n-CnH2n+1)4N, Spiropyran; X = C2O2S2, C2OS3, C2O3S)

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