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Magnetic frustration, muon probing, and hydrogen bonding in RBa2Cu3Oy
Physica C l&L 189 (1991) 1221- 1222 North-Holland
MAGNETIC FRUSTRATION, MUON PROBING, AND HYDROGEN BONDING IN RBa2CugOy
Wayne K. DAWSON and Care1 BOEKEMA, Physics Department, San Jose State University, San Jose, CA 95192, U.S.A. Roger L. LICHTI Texas Tech University, Lubbock, Texas 79409, U.S.A. D. Wayne COOKE Los Alamos National Laboratory, Los Atamos, New Mexico 87545, U.S. A.
Recent muon-spin-relaxation (f&R) studies on (PrxY+x)Ba2CugOy and H~YBa2Cu307 have confirmed the muonprobe site location near the BaO planes. Simifar behavior for H+ in Hydrogendoped YBa2Cdr307 Is seen as has been observed for the F+, namely bonding with oxygen. Thus, the knowledge of the muon-probe site in Rl23y improves the interpretations of the f&R magnetic studies in (PrxYf-x)1237 and the pSR vortex studies in R1237. Magnetic frustration appears to be the key to resolve,the physical origin of the CuO-based superconductivity.
1. INTRODUCTION
(H+). In zero applied field (PF), the obsewed elf preces-
The role of magnetism and superconductivity has been conspicuous in the high-Tc CuO superconductors.
sion frequency is proportional to the magnitude of the
The presence of magnetism makes the oxide supercon-
local field at the .&-stop site fp (MHz) = (13.55 MHz&G )I
ductors prime candidates for exploration using muonspin-relaxation
(t&R).
Using the location of the muon
3. EXPERIMENTAL BACKGROUND
stopping sites.213 interpretations have been made on the vortex structure4 in the mixed state of RBa2Cu307_8
research has been performed on (PrxYt_x)Ba2Cu30y
(R=Er. Eu, Gd, PrxYt_x), and the magnetic structures of
(PrxY23y: OIxrl,y=7;andx=
= 6). ErBa2Cu3Oy
PrBa2Cu308, PrBa2Cu307, and HxYBa2Cu307 (0 z x
(Erl23y:
237). and
c 1).2,3 The information obtained may help to elucidate the mechanism of superconductivity (SC) in the high-T,
the transition temperature dependence of Tc and/Or TN
cuprates.
with respect to x, the PrxY237 (0 -Zx c 1) reveals a com-
At Los Alomos National Laboratories (LAMPF),
y = 6.71, GdBa2Cu3Q? (
EuBa2Cu307.1166
When the f&R data is used to plot
plex picture of a superconducting phase (0 c x c 51, a spin-glass-like phase (5 < x < 541, and an antiferro-
2. MUON-SPIN-RELAXATION Muon-spin-relaxation
(uSR) is a form of magnetic
magnetic phase f.54 < x < i .j. A sh3ikif kind & x Cic-
resonance in which the positive muon (u+) is used as an
tionality is seen for YBa2Cu387_x PI 23(7-x)], and for
interstitial magnetic probe to measure the magnitude of
samples of ErI 23(7-x) (x = 0, 11.’ 577
the local magnetic fields at an atomic scale. The u+
Based upon the current data available from the Paul
cowalently bonds to the oxygens3 at temperatures below
Scherrer lnstitut (PSI),6 there is reason to presume that
150 K in oxide materials: a behavior similar to the proton
the phase diagram for HxYBa2Cu307 (HxYI237) exhibits
Work supported
by Research
Corporation.
C@21-4534/91/$03.50 0 1991 - Elsevier Scicncc t’ublishers B.V.
All rights rcservcd.
W.K. Dawsonet aL / Magneticfrustration, muon probinK and Izydrogenbonding in RBa2Cup y
1222
qualitatively similar behavior to'Y123(7-x) and PrxY237. The phase diagram correlation (0 < x < 1) suggest a similar driving mechanism can be attributed to PrxY237, Y123(7-x), and HxY1287. The simultaneous presence of both a spin-glass-like phase and a superconducting phase in PrxY1237 (,5 < x < .54) may indicate that high-To SC is resolvable in part
rate in the superconducting state, suggesting that the muon sees reduced RE spin fluctuations due to the shielding currents of the CuO planes. Further evidence can be seen in the temperature dependence in the mixed state of the IX+ frequency shift, which shows a RE contribution to the Meissner shift in mag R1237, and only the Meissner shift in n-mag R1237.
by the contributions from magnetic frustration. 6. INTERPRETATION OF HxY1237 4. MUON LOCALIZATION IN R123y STRUCTURES In all of the R123y structures observed to date,2, 3 the muon (g+) has been found to preferentially localize at the B2 site (see Fig. 1). Other sites, such as the B1 site, are also present but are less populated. Recent work using restricted HF-SCF cluster calculations have, conf:,'~ed that location of the ix+ at the B1, B2, and L12 sites (see Fig. 1)7
•
:.~.'~.~
Muon Rare
4 1 ~
~"~ "~'"
....
.
.
.
.
©o
The properties of HxY123y have been studied using I~SR at PSI. 8 For x • .5, there is evidence of long range magnetic ordering in g+ signal. Two signals are observed with saturation magnetization values of 2.3 MHz and 4.2 MHz. The intensity of the 4.2 MHz signal decreases for increasing H + doping while the intensity of the 2.3 MHz signal increases. Based upon the location of the g+-stop sites2, 3 in R123y, we attribute this change in asymmetry to the presence of H+ at the B2 site. As the B2 site becomes more populated with H +, the muon preferentially selects the B1 site, thus increasing the asymmetry at the site corresponding to the 2.3 MHz signal CONCLUSION The H+ occupies the same sites as the g+ in R123y. The p.SR data suggests the presence of localized shielding currents in the CuO planes. The phase diagrams for H, O and Pr doped R123y suggest that magnetic frustration is intertwined with SC. REFERENCES 1. D.W. Cooke et al., Phys Rev 41B (1990) 4801; J. Appl. Phys. 67 (1990) 5061; Hyperfine Interactions 63 (1990) 213.
FIGURE 1 Location of the g+-stop sites in RBa2Cu30 7. 5. INTERPRETATION OF THE VORTEX STRUCTURE Knowing the location of the muon-stop sites in R1237, we have been able to make a number of interpretations about the superconducting state of these oxides. From the data5,6 obtained for magnetic (mag) Gd1237, and Er1237, and nonmagnetic (nomag)Eu1237 there is clear evidence 4 of effects which can be attributed to local shielding currents. The evidence is shown by a reduction in the rare earth (RE) contribution to the IX+ relaxation
.
W.K. Dawson et al., Hyperfine Interactions 63 (1990).
3. W. K. Dawson et al., J. AppL Phys. 64 (1988) 5809; C. H. Halim et al., Physica 163B (1990) 453. .
~. L. Lichti et al., Phys. Rev. 43B (t391) 1154.
5. R.L. L=chti et al., j. Appl. Phys. 67 (1990) 5055. 6. D. W. Cooke c', =i., Phys Rev 41B (1989) 2748; Phys. Rev. 41B (1988) 9401. .
R. L. LichtJ et al., Hyperfine Interactions 63 (1990) 199.
8. C. Niedermayeret al., Phys. Rev. 40B (1989) 11386.
MAGNETIC FRUSTRATION, MUON PROBING, AND HYDROGEN BONDING IN RBa2CugOy
Wayne K. DAWSON and Care1 BOEKEMA, Physics Department, San Jose State University, San Jose, CA 95192, U.S.A. Roger L. LICHTI Texas Tech University, Lubbock, Texas 79409, U.S.A. D. Wayne COOKE Los Alamos National Laboratory, Los Atamos, New Mexico 87545, U.S. A.
Recent muon-spin-relaxation (f&R) studies on (PrxY+x)Ba2CugOy and H~YBa2Cu307 have confirmed the muonprobe site location near the BaO planes. Simifar behavior for H+ in Hydrogendoped YBa2Cdr307 Is seen as has been observed for the F+, namely bonding with oxygen. Thus, the knowledge of the muon-probe site in Rl23y improves the interpretations of the f&R magnetic studies in (PrxYf-x)1237 and the pSR vortex studies in R1237. Magnetic frustration appears to be the key to resolve,the physical origin of the CuO-based superconductivity.
1. INTRODUCTION
(H+). In zero applied field (PF), the obsewed elf preces-
The role of magnetism and superconductivity has been conspicuous in the high-Tc CuO superconductors.
sion frequency is proportional to the magnitude of the
The presence of magnetism makes the oxide supercon-
local field at the .&-stop site fp (MHz) = (13.55 MHz&G )I
ductors prime candidates for exploration using muonspin-relaxation
(t&R).
Using the location of the muon
3. EXPERIMENTAL BACKGROUND
stopping sites.213 interpretations have been made on the vortex structure4 in the mixed state of RBa2Cu307_8
research has been performed on (PrxYt_x)Ba2Cu30y
(R=Er. Eu, Gd, PrxYt_x), and the magnetic structures of
(PrxY23y: OIxrl,y=7;andx=
= 6). ErBa2Cu3Oy
PrBa2Cu308, PrBa2Cu307, and HxYBa2Cu307 (0 z x
(Erl23y:
237). and
c 1).2,3 The information obtained may help to elucidate the mechanism of superconductivity (SC) in the high-T,
the transition temperature dependence of Tc and/Or TN
cuprates.
with respect to x, the PrxY237 (0 -Zx c 1) reveals a com-
At Los Alomos National Laboratories (LAMPF),
y = 6.71, GdBa2Cu3Q? (
EuBa2Cu307.1166
When the f&R data is used to plot
plex picture of a superconducting phase (0 c x c 51, a spin-glass-like phase (5 < x < 541, and an antiferro-
2. MUON-SPIN-RELAXATION Muon-spin-relaxation
(uSR) is a form of magnetic
magnetic phase f.54 < x < i .j. A sh3ikif kind & x Cic-
resonance in which the positive muon (u+) is used as an
tionality is seen for YBa2Cu387_x PI 23(7-x)], and for
interstitial magnetic probe to measure the magnitude of
samples of ErI 23(7-x) (x = 0, 11.’ 577
the local magnetic fields at an atomic scale. The u+
Based upon the current data available from the Paul
cowalently bonds to the oxygens3 at temperatures below
Scherrer lnstitut (PSI),6 there is reason to presume that
150 K in oxide materials: a behavior similar to the proton
the phase diagram for HxYBa2Cu307 (HxYI237) exhibits
Work supported
by Research
Corporation.
C@21-4534/91/$03.50 0 1991 - Elsevier Scicncc t’ublishers B.V.
All rights rcservcd.
W.K. Dawsonet aL / Magneticfrustration, muon probinK and Izydrogenbonding in RBa2Cup y
1222
qualitatively similar behavior to'Y123(7-x) and PrxY237. The phase diagram correlation (0 < x < 1) suggest a similar driving mechanism can be attributed to PrxY237, Y123(7-x), and HxY1287. The simultaneous presence of both a spin-glass-like phase and a superconducting phase in PrxY1237 (,5 < x < .54) may indicate that high-To SC is resolvable in part
rate in the superconducting state, suggesting that the muon sees reduced RE spin fluctuations due to the shielding currents of the CuO planes. Further evidence can be seen in the temperature dependence in the mixed state of the IX+ frequency shift, which shows a RE contribution to the Meissner shift in mag R1237, and only the Meissner shift in n-mag R1237.
by the contributions from magnetic frustration. 6. INTERPRETATION OF HxY1237 4. MUON LOCALIZATION IN R123y STRUCTURES In all of the R123y structures observed to date,2, 3 the muon (g+) has been found to preferentially localize at the B2 site (see Fig. 1). Other sites, such as the B1 site, are also present but are less populated. Recent work using restricted HF-SCF cluster calculations have, conf:,'~ed that location of the ix+ at the B1, B2, and L12 sites (see Fig. 1)7
•
:.~.'~.~
Muon Rare
4 1 ~
~"~ "~'"
....
.
.
.
.
©o
The properties of HxY123y have been studied using I~SR at PSI. 8 For x • .5, there is evidence of long range magnetic ordering in g+ signal. Two signals are observed with saturation magnetization values of 2.3 MHz and 4.2 MHz. The intensity of the 4.2 MHz signal decreases for increasing H + doping while the intensity of the 2.3 MHz signal increases. Based upon the location of the g+-stop sites2, 3 in R123y, we attribute this change in asymmetry to the presence of H+ at the B2 site. As the B2 site becomes more populated with H +, the muon preferentially selects the B1 site, thus increasing the asymmetry at the site corresponding to the 2.3 MHz signal CONCLUSION The H+ occupies the same sites as the g+ in R123y. The p.SR data suggests the presence of localized shielding currents in the CuO planes. The phase diagrams for H, O and Pr doped R123y suggest that magnetic frustration is intertwined with SC. REFERENCES 1. D.W. Cooke et al., Phys Rev 41B (1990) 4801; J. Appl. Phys. 67 (1990) 5061; Hyperfine Interactions 63 (1990) 213.
FIGURE 1 Location of the g+-stop sites in RBa2Cu30 7. 5. INTERPRETATION OF THE VORTEX STRUCTURE Knowing the location of the muon-stop sites in R1237, we have been able to make a number of interpretations about the superconducting state of these oxides. From the data5,6 obtained for magnetic (mag) Gd1237, and Er1237, and nonmagnetic (nomag)Eu1237 there is clear evidence 4 of effects which can be attributed to local shielding currents. The evidence is shown by a reduction in the rare earth (RE) contribution to the IX+ relaxation
.
W.K. Dawson et al., Hyperfine Interactions 63 (1990).
3. W. K. Dawson et al., J. AppL Phys. 64 (1988) 5809; C. H. Halim et al., Physica 163B (1990) 453. .
~. L. Lichti et al., Phys. Rev. 43B (t391) 1154.
5. R.L. L=chti et al., j. Appl. Phys. 67 (1990) 5055. 6. D. W. Cooke c', =i., Phys Rev 41B (1989) 2748; Phys. Rev. 41B (1988) 9401. .
R. L. LichtJ et al., Hyperfine Interactions 63 (1990) 199.
8. C. Niedermayeret al., Phys. Rev. 40B (1989) 11386.