LONG-LIVING METASTABLE NON-EQUILIBRIUM STATES OF HTSC COMPOUNDS IN
TRANSIENT FOUR-PHOTON SPECTROSCOPY
Yu.V. Bobyrev, V.M. Petnikova, K.V. Rudenko, V.V. Shuvalov, A.V. Voronov
M.V.Lomonosov Moscow State University, Vorob’evy Gory, Moscow 119992, Russia
Phone: 7(095)9395035, Fax: 7(095)9393113, E-Mail: [email protected]
It will be shown that experimental data, obtained by pump-probe measurements in HTSC
compounds, can be interpreted in terms of long-living meta-stable non-equilibrium states with
specific energy gap and rather high (up to 600-800 K) electronic temperature.
LONG-LIVING META-STABLE NON-EQUILIBRIUM STATES OF HTSC COMPOUNDS IN
PUMP-PROBE SPECTROSCOPY
Yu.V. Bobyrev, V.M. Petnikova, K.V. Rudenko, V.V. Shuvalov, A.V. Voronov
M.V.Lomonosov Moscow State University, Vorob’evy Gory, Moscow 119992, Russia
Phone: 7(095)9395035, Fax: 7(095)9393113, E-Mail: [email protected]
In the paper, we are going to show that all experimental
data, obtained by different pump-probe techniques [1,2]
in HTSC compounds nearby the phase transition point
1,00
|e|, arb.un.
(M) 100K -> (M)
0,50
800K
600K
450K
300K
TC, can be interpreted in terms of long-living metastable non-equilibrium states with specific energy gap
0,00
(“pseudogap”) [3] and rather high (up to 600-800 K)
-0,50
electronic temperature Te. To do this different possible
situations with “normal” and “overheated” (due to the
, nm
-1,00
600
pumping absorption) electronic subsystem and with
(“S”) and without (“M”) energy gap of d-symmetry in
La-Cu-O band structure will be considered. The sample
1,00
3
nonlinear susceptibility   will be calculated by the
0,50
650
700
750
800
|e|, arb.un.
(S) 80K -> (M)
model, based on almost exact description of inter-band
electronic transitions to the states nearby the Fermi
surface [4]. Time delay will be simulated by Te gradual
800K
600K
450K
300K
100K
0,00
-0,50
decrease. Finally, we will show that predicted character
of modification of spectral dependence of the difference
3

, nm
-1,00
600
650
700
750
800
between the sample nonlinear response with and
without pumping (see left figures) corresponds to the
1,00
|e|, arb.un.
(S) 80K -> (S)
experimental data [1-3] in case when the energy gap
exists rather long time (3 ns and more) after excitation.
0,50
600K
450K
300K
150K
1. S.D. Brorson et al. Solid State Commun. 74, 1305
(1990)
2. S.V. Chekalin et al. Phys. Rev. Lett. 67, 3860 (1991);
0,00
-0,50
Yu.E. Lozovik et al. Laser Physics 9, 557 (1999)
3. A.V. Voronov et al. JETP 93, 1091 (2001)
4. L.P. Kuznetsova et al. J. of Raman Spectroscopy 31,
755 (2000)
, nm
-1,00
600
650
700
750
800