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SUMMARY:Exotic properties and emergent functionalities of chalcogenide Mot
 t insulators AM4Q8
DTSTART:20180427T151500
DTSTAMP:20260505T014920Z
UID:679e7555a38a0f3f560f524cb4d59b573ed1b921ca9eba6304d6a599
CATEGORIES:Conferences - Seminars
DESCRIPTION:Laurent Cario  Institut de Matériaux Jean Rouxel (IMN) Nante
 s\, France \nThe AM4Q8 (A = Ga\, Ge\; M = V\, Nb\, Ta\, Mo\; Q = S\, Se)
  compounds represent a family of narrow gap Mott insulators with very inte
 resting electronic properties. These compounds exhibit a lacunar spinel st
 ructure with tetrahedral transition metal clusters M4 [1]. Compare to mo
 st other inorganic Mott insulators\, the AM4Q8 compounds show very small 
 Mott-Hubbard gap (0.1-0.3 eV) as the electronic repulsion occurs on the s
 cale of these tetrahedral clusters and not on the scale of single atoms [2
 ]. As a consequence these compounds show a great variety of ground states 
 and astonishing electronic properties depending on clusters filling\, com
 pression or distortion. GeV4S8 for example exhibit a multiferroic behavio
 ur related to an orbital ordering on the clusters [3]. GaTa4Se8 and GaNb4
 Se8 undergo a bandwidth-control Insulator to Metal Transition (IMT) and 
 superconductivity when placed under external pressure [2\, 4]. The substit
 ution of V per Ti in the GaV4S8 leads to an IMT driven by disorder on the
  clusters and to the emergence of a half ferromagnetic metal [5]. While c
 hemical doping of the ferromagnetic Mott insulator Ga1-xGexV4S8 leads to 
 a bulk\, colossal and negative magnetoresistance that may be understood o
 n the basis of the cluster distortion at low temperature [6]. Finally\, th
 e AM4Q8 compounds reveal a striking resistive switching above a threshold
  electric field of a few kV/cm which is related to the breakdown of the M
 ott insulating state at the nanoscale [7]. This phenomenon opens new funct
 ionalities that may be employed to build up a new type of Resistive Random
  Access Memory (RRAM) [8] or an artificial neurons [9]. \n\n\nReferences
 :\n\n[1] Ben Yaich\, H. et al. (1984) J. Less-Common Met. 102\, 9\; \
 n[2] Abd-Elmeguid\, M. M. et al. (2004) Phys. Rev. Lett. 93\, 026401\;
  Ta Phuoc\, et al. (2013) Phys. Rev. Lett.\, 110 (3)\, 037401. Jeong\, M. 
 Y. et al. (2017) Nature Commun. 10.1038/s41467-017-00841-9 \n[3] Sing
 h\, K. et al. (2014) Phys. Rev. Lett. 113 (13)\, 137602. \n[4] Pocha\
 , R. et al. (2005) J. Am. Chem. Soc. 127\, 8732\; Camjayi\, A et al.
  (2014) Phys. Rev. Let.\, 113 (8)\, 086404. \n[5] Vaju\, C. et al. (20
 08) Chem. Mater. 20\, 2382\; Dorolti\, E. et al. (2010) J. Am. Chem. 
 Soc. 132\, 5704 \n[6] Janod\, E. et al. (2015) Chemistry of Materials\
 , 27 (12)\, 4398. \n[7] Janod\, E. et al. (2015) Adv. Funct. Mater. 25\
 , 6287. Guiot\, V. et al. (2013) Nat Commun 4\, 1722. \n[8] Vaju C. e
 t al.\, Adv. Mat. 2008\, 20 : 2760. L. Cario et al.\, Adv. Mat. 2010\, 22 
 : 5193. \n[9] Stoliar P. et al. Adv. Funct. Mater. 27\, 1604740(1 (2017).
  
LOCATION:CE 1 5 https://plan.epfl.ch/?room==CE%201%205
STATUS:CONFIRMED
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