Crystal structure, T-P phase diagram and magnetotransport properties of new organic metal
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Crystal structure, T-P phase diagram and magnetotransport properties of new organic metal  -(BETS) 2 Mn[N(CN) 2 ] 3. Vladimir Zverev 1 , Nataliya Kushch 2 , Eduard Yagubskii 2 , Lev Buravov 2 , Salavat Khasanov 1 , Rimma Shibaeva 1 , Mark Kartsovnik 3 , and Werner Biberacher 3

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Crystal structure, T-P phase diagram and magnetotransport properties of new organic metal

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Crystal structure t p phase diagram and magnetotransport properties of new organic metal

Crystal structure, T-P phase diagram and magnetotransport properties of new organic metal

-(BETS)2Mn[N(CN)2]3

Vladimir Zverev1, Nataliya Kushch2, Eduard Yagubskii2, Lev Buravov2, Salavat Khasanov1, Rimma Shibaeva1,

Mark Kartsovnik3, and Werner Biberacher3

1Institute of Solid State Physics, Chernogolovka

2Institute of Problems of Chemical Physics,

Chernogolovka

3Walther-Meissner-Institut, Bayerishe Akademie der

Wissenschaften, Garching, Germany


Crystal structure t p phase diagram and magnetotransport properties of new organic metal

Crystal structure, T-P phase diagram and magnetotransport properties of new organic metal

-(BETS)2Mn[N(CN)2]3

We deal with hybrid multifunctional molecular material combining conducting and magnetic properties in the same crystal lattice.

Electrical conductivity is provided by an organic radical cation subsystem

Magnetism is provided by an anionic subsystem, containing magnetic transition metal (Mn).


Crystal structure t p phase diagram and magnetotransport properties of new organic metal

ab

Crystal structure of -(BETS)2Mn[N(CN)2]3 projected on the ac-plane (a); Projection of the anion layer on the bc-plane (b)

The structure is characterized by the alternation of -type cation layers with polymeric anion layers along the a axis. In the anion layer, each Mn2+ion has an octahedral coordination and is linked with six neighboring Mn2+ions via N(CN)2- bridges.


Crystal structure t p phase diagram and magnetotransport properties of new organic metal

(0 1 -3)

q = 0.42 b*

(0 -1 -3)

+q

-q

Y

Y

-(BETS)2Mn[N(CN)2]3

T = 90K

1-D section of the diffraction pattern along

the line Y = kb* - 3c*

Diffraction pattern in the (a*,b*) plane.

The arrows indicate on the satellite reflections.

There is a phase transition near 102 K resulting in the formation of incommensurate superstructure: below 102K X-ray diffraction patterns show weak satellite reflections which can be described by the incommensurate wave vector q = 0.42b*.

This superstructure survives down to 15 K!


Crystal structure t p phase diagram and magnetotransport properties of new organic metal

Y

-(BETS)2Mn[N(CN)2]3

T = 90K

Diffraction pattern in the (a*,b*) plane.

The arrows indicate on the satellite reflections.

There is a phase transition near 102 K resulting in the formation of incommensurate superstructure: below 102K X-ray diffraction patterns show weak satellite reflections which can be described by the incommensurate wave vector q = 0.42b*.

This superstructure survives down to 15 K!


Crystal structure t p phase diagram and magnetotransport properties of new organic metal

Temperature dependence of the interplane resistance

of -(BETS)2Mn[N(CN)2]3crystal at ambient pressure


Crystal structure t p phase diagram and magnetotransport properties of new organic metal

Temperature dependence of the interplane resistance

of -(BETS)2Mn[N(CN)2]3crystal at ambient pressure

The M-I transition takes place in electron subsystem because at T=TM-I there are no changes in the X-ray crystal structure!


Crystal structure t p phase diagram and magnetotransport properties of new organic metal

Susceptibility  in -(BETS)2[Mn(N(CN)2)3]


Crystal structure t p phase diagram and magnetotransport properties of new organic metal

Susceptibility  in -(BETS)2[Mn(N(CN)2)3]

There is no peculiarity on (T) dependence at TM-I


Crystal structure t p phase diagram and magnetotransport properties of new organic metal

Susceptibility  in -(BETS)2[Mn(N(CN)2)3]

There is no peculiarity on (T) dependence at TM-I

But in 1H NMR and torque experiments there are some peculiarities indicating to the formation of a short-range order of Mn spins at TM-I !

See Oleg Vyaselev’s Poster!


Crystal structure t p phase diagram and magnetotransport properties of new organic metal

Pressure induced metal-insulator andsuperconductor-insulator transitions in -(BETS)2Mn[N(CN)2]3


Crystal structure t p phase diagram and magnetotransport properties of new organic metal

T – P phase diagram

Superconducting and insulating phases coexist at (0.4 < P < 0.5) kbar.


Shubnikov de haas oscillations

Shubnikov – de Haas oscillations


Shubnikov de haas oscillations1

Shubnikov – de Haas oscillations


Sdh oscillations in 1 b scale

SdH oscillations in 1/B scale


Temperature dependence of sdh oscillation amplitude

Temperature dependence of SdH oscillation amplitude


Pressure dependences of sdh oscillation frequency and the cyclotron mass

Pressure dependences of SdH oscillation frequency and the cyclotron mass


Energy spectrum and the fermi surface extended h ckel method

Energy spectrum and the Fermi-surface (extended Hückel method)

The SdH oscillation frequency corresponds to about 1.5% of the BZ cross section.


Crystal structure t p phase diagram and magnetotransport properties of new organic metal

(0 1 -3)

q = 0.42 b*

(0 -1 -3)

+q

-q

Y

Y

-(BETS)2Mn[N(CN)2]3

T = 90K

1-D section of the diffraction pattern along

the line Y = kb* - 3c*

Diffraction pattern in the (a*,b*) plane.

The arrows indicate on the satellite reflections.

There is a phase transition near 102 K resulting in the formation of incommensurate superstructure: below 102K X-ray diffraction patterns show weak satellite reflections which can be described by the incommensurate wave vector q = 0.42b*.

This superstructure survives down to 15 K!


Energy spectrum and the fermi surface extended h ckel method1

Energy spectrum and the Fermi-surface (extended Hückel method)

The SdH oscillation frequency corresponds to about 1.5% of the BZ cross section.

The small pocket may arise due to the existence of the superstructure!

q=0.42b*


Crystal structure t p phase diagram and magnetotransport properties of new organic metal

Conclusions

  • Crystal structure and magnetotransport properties of new organic metal -(BETS)2Mn[N(CN)2]3 were studied.

  • A phase transition near 102 K resulting in the formation of incommensurate superstructure below 102Kwas found.

  • At T  27K a structureless phase transition in electron system was observed at ambient pressure.

  • A moderate pressure P  0.5 kbar suppresses the metal-insulator transition and the compound becomes metallic down to low temperatures and superconducting with Tc= 5.8 K.

  • T-P phase diagram was plotted in the pressure range 0-2.5 kbar.

  • In the metallic state Shubnikov-de Haas oscillations which could be related to the small pockets of the FS were observed .


Crystal structure t p phase diagram and magnetotransport properties of new organic metal

Temperature dependence of the interplane resistance

of -(BETS)2Mn[N(CN)2]3crystal at ambient pressure


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