(EMA-S12-021-2013) Nanoscale phase inhomogeneities in iron ...

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15 Νοε 2013 (πριν από 3 χρόνια και 6 μήνες)

82 εμφανίσεις

(EMA
-
S12
-
021
-
2013)


Nanos
cale phase inhomogeneities in iron
-
based

selenides: Implications on the electronic
structure and

magnetic ground state (Invited)


C. Cantoni*, A. F. May, M. A. Mich
ael, A. Safa
-
Sefat, B. C. Sales.


Oak Ridge

National Laboratory,
USA


Years of experimental work on cuprates have led to a vast understanding

of the effect of

nanoscale strain on superconducting properties.

Strain relief mechanisms at interfaces involve
oxygen vacancies

and structural defects, which have a large effect

on Tc and Jc. In the

newest
class of Fe
-
based superconductors, A1
-
yFe2
-
xSe2 (A= alkali

metal, alkaline
-
earth metal), there
is considerable evidence that Fe

vacancy order, nanoscale phase separation, and associated lattice

strain might be necessary conditi
ons for superconductivity to arise.

This presentation will focus
on nanoscale inhomogeneities and their

implication on the electronic structure of high
-
Tc
superconductors

and parent compounds as revealed by aberration corrected STEM

and EELS.
Examples from

cuprates and different Fe
-
based superconductor

families will be discussed in an
effort to identify key signatures

of superconductivity and the interplay with magnetism. In
particular,

it will be shown that nanoscale phase separation in ordered and disorde
red

vacancy
regions leads to a different magnetic ground state

than the ground state of single
-
phase
counterparts in TlFe1.6Se2,

suggesting that magnetoelastic coupling between different phases is

important for the emergence of superconductivity in
A1
-
yFe2
-
xSe2.

Research sponsored by US
DOE Office of Science, Materials Science

and Engineering Division.