Dependence of Band Renormalization Effect on the Number of Copper-oxide Layers in Tl-based Copper-oxide Superconductor using Angle-resolved Photoemission Spectroscopy Page: 3 of 4
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"-', 'j ' ' ' '
-0.1 0.0 0.1 -0.1 0.0 0.1
-0.05 - ,*
-0.2 -0.1 0.0 0.1
-0.2 -0.1 0.0 0.1
Momentum, k - kF (A1
-0.2 -0.1 0.0 0.1
FIG. 3: Band dispersions of T1-2201 near the Fermi surface
along the cuts indicated in the upper-right panel.
antinodal peak below T, is indeed related to the onset of
the superconductivity. We note that this observation is
consistent with other cuprates with high Tc, such as opti-
mally doped Bi-2212, Bi-2223 , and overdoped T1-2201
with T= 74K . Our results confirm that the emer-
gence of a sharp peak in the superconducting state is one
of the universal properties of superconducting cuprates
with high transition temperatures.
Next, we will discuss the momentum dependence of the
band renormalization effect. In Fig. 2, band dispersions
of T1-2212 at several different momentum positions on
the Fermi surface are shown. A sudden change of the
dispersion slopes, a kink at an energy of approximately
50-70 meV is observed near the nodal region (Al and
A2) . When moving from the nodal region toward antin-
odal region (A3-A4), the "kink" becomes more dramatic
and eventually breaks the band dispersion causing an in-
tensity depletion in the image plot of the spectrum at
a characteristic energy of approximately 70 meV (black
dashed line). The representing EDCs of the broken-up
band dispersion at A4 are plotted in Fig. 4 (a). When the
band disperses toward higher binding energy (along the
direction of the arrow), the sharp peak close to EF starts
to diminish and the spectral lineshape at higher binding
energy starts to deviate from a straight line, indicating
convex curvature of representing a "hump".
To emphasize the structure of the spectra, we simply
define the peak position as the maximum of the sharp
peak when it is still discernible in the spectrum, while
hump position is set as the position where the spectrum
starts to deviate from the apparent straight line drawn
from the highest binding energy of our data. It is clear
that the band dispersion breaks into two branches: a
sharp peak branch (short bars) and a broad hump branch
(open circles). Between these two features is a "dip" in
-02 -01 00
E - EF (eV)
-02 -01 00
E - EF (eV)
(c)TI-2201 (d) TI-1223
-02 -01 00 -02 -01 00
E -EF (eV) E -EF (eV)
FIG. 4: The representing EDCs of (a) A4 for T1-2201, (b)
B4 for T1-2212, and (d) C4 for T1-1223 along the black arrow
indicated in Fig. 3, 2, and 5, respectively. (c) EDCs for Tl-
2201 and T1-1223 near (7r,0) (red point in the inset). Short
vertical bars indicate the peak position. Open circles indicate
the hump position. Vertical dashed line indicate the position
of the "dip". The dashed lines in (a) and (c) are guides-to-
the-eye to make the "hump" more discernible.
the EDC, which corresponds to the intensity depletion
region seen in the image plot of spectrum (Fig. 2). This
broken-up dispersion and the peak-dip-hump structure
are seen in a wide range of the Fermi surface: from ap-
proximately the midpoint between the node and antin-
ode to the antinode as marked and displayed in A3-A5
of Fig. 2. The fact that the dip is located at a similar
energy scale (black dashed line in Fig. 2) for A3-A5 sug-
gests that the renormalization effect is dominated by one
sharp bosonic mode in this momentum region.
Contrarily, the single layer T1-2201 system exhibits
a qualitatively different momentum dependence of the
renormalization effect. As shown in Fig. 3, a "kink" in
the dispersion around 50-70 meV is also observed near
the nodal region (B1 and B2). This dispersion kink be-
comes harder to be resolved near the antinodal region; as
shown from B3 to B5 (from intermediate region to antin-
odal region), neither an apparent "kink" in the dispersion
nor an intensity depletion in the image plot of the spectra
can be discerned. Indeed, as plotted in Fig. 4 (b), the
band dispersion at B4, which is located at a similar mo-
mentum position of A4, has only one branch consisting
a peak structure with no sign of a peak-dip-hump struc-
ture as those observed in T1-2212 compounds. The lack
of a peak-dip-hump lineshape persists to the antinode as
oppose to that of T1-2212 (Fig. 4 (c)).
To further verify the observed distinct momentum de-
pendence of the renormalization effect between single
layer and double layer Tl-based cuprates, we performed
measurements on the Tl-based tri-layer cuprate, T1-1223,
which are shown in Fig. 5. The momentum dependence
of renormalization effect is found to be qualitatively sim-
ilar to those observed in T1-2212 (Fig. 2); a broken-up
dispersion with a dominant characteristic energy scale of
50-70 meV can be identified (black dashed line in Fig. 5).
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Lee, Wei-Sheng. Dependence of Band Renormalization Effect on the Number of Copper-oxide Layers in Tl-based Copper-oxide Superconductor using Angle-resolved Photoemission Spectroscopy, article, June 2, 2010; [California]. (digital.library.unt.edu/ark:/67531/metadc1013839/m1/3/: accessed October 16, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.