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Effect of pressure on the electrical resistivity ofCeZn3P3
To cite this article A Yamada et al 2010 J Phys Conf Ser 215 012031
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Effect of Pressure on the Electrical Resistivity of
CeZn3P3
A Yamada13lowast N Hara2 K Matsubayashi3 K Munakata3
C Ganguli3 A Ochiai2 T Matsumoto3 Y Uwatoko3
1Graduate School of Science and Engineering Saitama University Saitama 338-8570 Japan2Department of Physics Faculty of Science Tohoku University Miyagi 980-8578 Japan3Institute for Solid State Physics The University of Tokyo Chiba 277-8581 Japan
E-mail a-yamadaisspu-tokyoacjp
AbstractWe have measured the electrical resistivity of CeZn3P3 single crystals under pressure up to
19 GPa for temperature down to 04 K At ambient pressure the electrical resistivity showsa semiconducting behavior with an energy gap Eg sim 1800 K We have found that the Eg
monotonically decreases with increasing pressure and possibly disappears at around 20 GPa
1 INTRODUCTIONCeZn3P3 crystallizes in the ScAl3C3-type structure (space group P63mmc) with the latticeconstants a = 4051 A and c = 20019 A Ce occupies a single site forming a two-dimensionaltriangular lattice [1] The Ce layer on the c-plane is separated from the next Ce layer bya distance of about 10 A by Zn and P ions The magnetic susceptibility obeys Curie-Weisslaw with paramagnetic Curie constant θP = -66 K At low temperature CeZn3P3 undergoesan antiferromagnetic ordering at TN = 08 K The entropy of the magnetic contribution issim04Rln2 atTN and reaches Rln2 around 10 K suggesting that CeZn3P3 has the short rangemagnetic interaction above TN [2 3] As for the transport properties the resistivity showsthe semiconductor-like temperature dependence with an activation energy of about 1800 KHere we investigate the pressure effect of the energy gap of CeZn3P3 and observed a continuossuppression of the energy gap under pressure
2 EXPERIMENTALSingle crystals of CeZn3P3 were grown by Zn self-flux method The electrical resistivity wasmeasurement by a standard four-probe dc technique High pressure was generated by using twotypes of pressure cells a cubic anvil high pressure cell (CAC) and a diamond anvil cell (DAC) [5]In the case of CAC the sample was cut into bar shape with a typical dimension of 08times03times015mm3 and the electrical resistivity was measured with the current flowing along a-axis Thesample was placed in a Teflon capsule filled with a 11 mixture of Fluorinert FC70 and FC77 asa pressure transmitting medium This measurement was performed in a 4He cryostat down to2 K with a maximum pressure of 11 GPa The applied force to the sample was kept constantduring the measurement by cooling and warming runs A diamond anvil cell (DAC) was used forelectrical resistivity measurements under high pressures up to 19 GPa and temperatures down
Joint AIRAPT-22 amp HPCJ-50 IOP PublishingJournal of Physics Conference Series 215 (2010) 012031 doi1010881742-65962151012031
ccopy 2010 IOP Publishing Ltd 1
to 04 K using a 3He refrigerator system We used a mixture of diamond power and epoxy forinsulating gaskets The hole in the gasket was filled with powder sample with a small ruby chipused as a pressure marker [4]
3 RESULTS AND DISCUSSIONFigure 1 shows the temperature dependence of the electrical resistivity ρ(T ) of CeZn3P3 underpressure up to 11 GPa using CAC At 2 GPa the ρ(T ) shows semiconductor like temperaturedependence as observed at ambient pressure [2] The resistivity at room temperature initiallyincreases with applying pressure and then starts to decrease above 6 GPa In this pressurerange low temperature resistivity tends to saturate and shows a hump around 80 K As shown inFig 2 ρ(T ) follows activation behavior at high temperatures while low temperature resistivitychanges variable range hopping regime as inferred by the so-called Tminus14-law Here we estimatethe activation energy defined by ρ(T ) prop exp(Eg2T ) from the maximum slope in the linearportion on the Arrhenius plot (see the dashed lines in Fig 2) We find that the activationenergy monotonically decreases with increasing pressure and Eg reaches sim450 K at 11 GPa
In order to reveal the P -dependence of Eg at higher pressures the achievable maximumpressure was extended using DAC Figure 3 shows the temperature dependence of the relativeresistance log R of CeZn3P3 The overall feature in ρ(T ) is qualitatively the same as thatobtained using CAC The semiconducting behavior is strongly suppressed by applying pressurehowever Eg is still finite at the highest pressure of 19 GPa
In Fig 4 we summarize the P -dependence of Eg presented above As the pressure increasesEg monotonically decreases and seem to disappears at approximately 20 GPa We note that wefound no resistive anomaly corresponding to the magnetic ordering temperature of Ce ions inthese measurement However the interplay between magnetism and the energy gap is a subjectto be solved We believe that it deserves a further investigation
01
1
10
100
r (Ω
cm
)
300250200150100500
T (K)
20 GPa35
60
90
110
CeZn3P3
Figure 1 The temperature dependence of the electrical resistivity ρ(T ) of CeZn3P3 underpressure using cubic anvil cell
Joint AIRAPT-22 amp HPCJ-50 IOP PublishingJournal of Physics Conference Series 215 (2010) 012031 doi1010881742-65962151012031
2
6
4
2
0
-2
In r
14x10-3
12108642
1T (K-1
)
35
90
60
20 GPa
110
CeZn3P3
Figure 2 ln ρ as a function of inverse temperature 1T The dashed straight line represents theArrhenius law for the maximum slope range between the linear portion under various pressure
10-1
100
101
102
103
104
105
106
R (
Ω)
300250200150100500
T (K)
5 GPa
CeZn3P3
7
11
14
19
Figure 3 The temperature dependence of the electrical resistivity ρ(T ) of CeZn3P3 underpressure using DAC
Joint AIRAPT-22 amp HPCJ-50 IOP PublishingJournal of Physics Conference Series 215 (2010) 012031 doi1010881742-65962151012031
3
2000
1500
1000
500
0
Eg
(K)
2520151050
P (GPa)
CeZn3P3 cubic anvil cell diamond anvil cell
Figure 4 Pressure dependence of Eg deduced from high pressure experiments using CAC(circles) and DAC (squares)
AcknowledgementWe would like to thank Prof M Abd-Elmeguid for useful technics of the DAC This workwas partially supported by the matching fund subsidy from the Ministry of Education CultureSports Science and Technology (MEXT) of the Japanese Government and by Grant-in-Aid ForScientific Research (21340092 20102008 and 19GS0205) of Japan Society for the Promotion ofScience(JSPS)
References[1] Nientiedt Andre T and Jeitschko W 1999 J Solid State Chem 146 478[2] Hara N JPS 2008 Autumn Meeting 20pQH-10[3] Hara N and Ochiai A private communication[4] Zha C S Mao H K and Hemley R J 2000 Proc Natl Acad Sci 97 13494[5] Mori N Okayama Y Takahashi H Haga Y and Suzuki T 1993 Jpn J Appl Phys Series 8
182
Joint AIRAPT-22 amp HPCJ-50 IOP PublishingJournal of Physics Conference Series 215 (2010) 012031 doi1010881742-65962151012031
4
Effect of Pressure on the Electrical Resistivity of
CeZn3P3
A Yamada13lowast N Hara2 K Matsubayashi3 K Munakata3
C Ganguli3 A Ochiai2 T Matsumoto3 Y Uwatoko3
1Graduate School of Science and Engineering Saitama University Saitama 338-8570 Japan2Department of Physics Faculty of Science Tohoku University Miyagi 980-8578 Japan3Institute for Solid State Physics The University of Tokyo Chiba 277-8581 Japan
E-mail a-yamadaisspu-tokyoacjp
AbstractWe have measured the electrical resistivity of CeZn3P3 single crystals under pressure up to
19 GPa for temperature down to 04 K At ambient pressure the electrical resistivity showsa semiconducting behavior with an energy gap Eg sim 1800 K We have found that the Eg
monotonically decreases with increasing pressure and possibly disappears at around 20 GPa
1 INTRODUCTIONCeZn3P3 crystallizes in the ScAl3C3-type structure (space group P63mmc) with the latticeconstants a = 4051 A and c = 20019 A Ce occupies a single site forming a two-dimensionaltriangular lattice [1] The Ce layer on the c-plane is separated from the next Ce layer bya distance of about 10 A by Zn and P ions The magnetic susceptibility obeys Curie-Weisslaw with paramagnetic Curie constant θP = -66 K At low temperature CeZn3P3 undergoesan antiferromagnetic ordering at TN = 08 K The entropy of the magnetic contribution issim04Rln2 atTN and reaches Rln2 around 10 K suggesting that CeZn3P3 has the short rangemagnetic interaction above TN [2 3] As for the transport properties the resistivity showsthe semiconductor-like temperature dependence with an activation energy of about 1800 KHere we investigate the pressure effect of the energy gap of CeZn3P3 and observed a continuossuppression of the energy gap under pressure
2 EXPERIMENTALSingle crystals of CeZn3P3 were grown by Zn self-flux method The electrical resistivity wasmeasurement by a standard four-probe dc technique High pressure was generated by using twotypes of pressure cells a cubic anvil high pressure cell (CAC) and a diamond anvil cell (DAC) [5]In the case of CAC the sample was cut into bar shape with a typical dimension of 08times03times015mm3 and the electrical resistivity was measured with the current flowing along a-axis Thesample was placed in a Teflon capsule filled with a 11 mixture of Fluorinert FC70 and FC77 asa pressure transmitting medium This measurement was performed in a 4He cryostat down to2 K with a maximum pressure of 11 GPa The applied force to the sample was kept constantduring the measurement by cooling and warming runs A diamond anvil cell (DAC) was used forelectrical resistivity measurements under high pressures up to 19 GPa and temperatures down
Joint AIRAPT-22 amp HPCJ-50 IOP PublishingJournal of Physics Conference Series 215 (2010) 012031 doi1010881742-65962151012031
ccopy 2010 IOP Publishing Ltd 1
to 04 K using a 3He refrigerator system We used a mixture of diamond power and epoxy forinsulating gaskets The hole in the gasket was filled with powder sample with a small ruby chipused as a pressure marker [4]
3 RESULTS AND DISCUSSIONFigure 1 shows the temperature dependence of the electrical resistivity ρ(T ) of CeZn3P3 underpressure up to 11 GPa using CAC At 2 GPa the ρ(T ) shows semiconductor like temperaturedependence as observed at ambient pressure [2] The resistivity at room temperature initiallyincreases with applying pressure and then starts to decrease above 6 GPa In this pressurerange low temperature resistivity tends to saturate and shows a hump around 80 K As shown inFig 2 ρ(T ) follows activation behavior at high temperatures while low temperature resistivitychanges variable range hopping regime as inferred by the so-called Tminus14-law Here we estimatethe activation energy defined by ρ(T ) prop exp(Eg2T ) from the maximum slope in the linearportion on the Arrhenius plot (see the dashed lines in Fig 2) We find that the activationenergy monotonically decreases with increasing pressure and Eg reaches sim450 K at 11 GPa
In order to reveal the P -dependence of Eg at higher pressures the achievable maximumpressure was extended using DAC Figure 3 shows the temperature dependence of the relativeresistance log R of CeZn3P3 The overall feature in ρ(T ) is qualitatively the same as thatobtained using CAC The semiconducting behavior is strongly suppressed by applying pressurehowever Eg is still finite at the highest pressure of 19 GPa
In Fig 4 we summarize the P -dependence of Eg presented above As the pressure increasesEg monotonically decreases and seem to disappears at approximately 20 GPa We note that wefound no resistive anomaly corresponding to the magnetic ordering temperature of Ce ions inthese measurement However the interplay between magnetism and the energy gap is a subjectto be solved We believe that it deserves a further investigation
01
1
10
100
r (Ω
cm
)
300250200150100500
T (K)
20 GPa35
60
90
110
CeZn3P3
Figure 1 The temperature dependence of the electrical resistivity ρ(T ) of CeZn3P3 underpressure using cubic anvil cell
Joint AIRAPT-22 amp HPCJ-50 IOP PublishingJournal of Physics Conference Series 215 (2010) 012031 doi1010881742-65962151012031
2
6
4
2
0
-2
In r
14x10-3
12108642
1T (K-1
)
35
90
60
20 GPa
110
CeZn3P3
Figure 2 ln ρ as a function of inverse temperature 1T The dashed straight line represents theArrhenius law for the maximum slope range between the linear portion under various pressure
10-1
100
101
102
103
104
105
106
R (
Ω)
300250200150100500
T (K)
5 GPa
CeZn3P3
7
11
14
19
Figure 3 The temperature dependence of the electrical resistivity ρ(T ) of CeZn3P3 underpressure using DAC
Joint AIRAPT-22 amp HPCJ-50 IOP PublishingJournal of Physics Conference Series 215 (2010) 012031 doi1010881742-65962151012031
3
2000
1500
1000
500
0
Eg
(K)
2520151050
P (GPa)
CeZn3P3 cubic anvil cell diamond anvil cell
Figure 4 Pressure dependence of Eg deduced from high pressure experiments using CAC(circles) and DAC (squares)
AcknowledgementWe would like to thank Prof M Abd-Elmeguid for useful technics of the DAC This workwas partially supported by the matching fund subsidy from the Ministry of Education CultureSports Science and Technology (MEXT) of the Japanese Government and by Grant-in-Aid ForScientific Research (21340092 20102008 and 19GS0205) of Japan Society for the Promotion ofScience(JSPS)
References[1] Nientiedt Andre T and Jeitschko W 1999 J Solid State Chem 146 478[2] Hara N JPS 2008 Autumn Meeting 20pQH-10[3] Hara N and Ochiai A private communication[4] Zha C S Mao H K and Hemley R J 2000 Proc Natl Acad Sci 97 13494[5] Mori N Okayama Y Takahashi H Haga Y and Suzuki T 1993 Jpn J Appl Phys Series 8
182
Joint AIRAPT-22 amp HPCJ-50 IOP PublishingJournal of Physics Conference Series 215 (2010) 012031 doi1010881742-65962151012031
4
to 04 K using a 3He refrigerator system We used a mixture of diamond power and epoxy forinsulating gaskets The hole in the gasket was filled with powder sample with a small ruby chipused as a pressure marker [4]
3 RESULTS AND DISCUSSIONFigure 1 shows the temperature dependence of the electrical resistivity ρ(T ) of CeZn3P3 underpressure up to 11 GPa using CAC At 2 GPa the ρ(T ) shows semiconductor like temperaturedependence as observed at ambient pressure [2] The resistivity at room temperature initiallyincreases with applying pressure and then starts to decrease above 6 GPa In this pressurerange low temperature resistivity tends to saturate and shows a hump around 80 K As shown inFig 2 ρ(T ) follows activation behavior at high temperatures while low temperature resistivitychanges variable range hopping regime as inferred by the so-called Tminus14-law Here we estimatethe activation energy defined by ρ(T ) prop exp(Eg2T ) from the maximum slope in the linearportion on the Arrhenius plot (see the dashed lines in Fig 2) We find that the activationenergy monotonically decreases with increasing pressure and Eg reaches sim450 K at 11 GPa
In order to reveal the P -dependence of Eg at higher pressures the achievable maximumpressure was extended using DAC Figure 3 shows the temperature dependence of the relativeresistance log R of CeZn3P3 The overall feature in ρ(T ) is qualitatively the same as thatobtained using CAC The semiconducting behavior is strongly suppressed by applying pressurehowever Eg is still finite at the highest pressure of 19 GPa
In Fig 4 we summarize the P -dependence of Eg presented above As the pressure increasesEg monotonically decreases and seem to disappears at approximately 20 GPa We note that wefound no resistive anomaly corresponding to the magnetic ordering temperature of Ce ions inthese measurement However the interplay between magnetism and the energy gap is a subjectto be solved We believe that it deserves a further investigation
01
1
10
100
r (Ω
cm
)
300250200150100500
T (K)
20 GPa35
60
90
110
CeZn3P3
Figure 1 The temperature dependence of the electrical resistivity ρ(T ) of CeZn3P3 underpressure using cubic anvil cell
Joint AIRAPT-22 amp HPCJ-50 IOP PublishingJournal of Physics Conference Series 215 (2010) 012031 doi1010881742-65962151012031
2
6
4
2
0
-2
In r
14x10-3
12108642
1T (K-1
)
35
90
60
20 GPa
110
CeZn3P3
Figure 2 ln ρ as a function of inverse temperature 1T The dashed straight line represents theArrhenius law for the maximum slope range between the linear portion under various pressure
10-1
100
101
102
103
104
105
106
R (
Ω)
300250200150100500
T (K)
5 GPa
CeZn3P3
7
11
14
19
Figure 3 The temperature dependence of the electrical resistivity ρ(T ) of CeZn3P3 underpressure using DAC
Joint AIRAPT-22 amp HPCJ-50 IOP PublishingJournal of Physics Conference Series 215 (2010) 012031 doi1010881742-65962151012031
3
2000
1500
1000
500
0
Eg
(K)
2520151050
P (GPa)
CeZn3P3 cubic anvil cell diamond anvil cell
Figure 4 Pressure dependence of Eg deduced from high pressure experiments using CAC(circles) and DAC (squares)
AcknowledgementWe would like to thank Prof M Abd-Elmeguid for useful technics of the DAC This workwas partially supported by the matching fund subsidy from the Ministry of Education CultureSports Science and Technology (MEXT) of the Japanese Government and by Grant-in-Aid ForScientific Research (21340092 20102008 and 19GS0205) of Japan Society for the Promotion ofScience(JSPS)
References[1] Nientiedt Andre T and Jeitschko W 1999 J Solid State Chem 146 478[2] Hara N JPS 2008 Autumn Meeting 20pQH-10[3] Hara N and Ochiai A private communication[4] Zha C S Mao H K and Hemley R J 2000 Proc Natl Acad Sci 97 13494[5] Mori N Okayama Y Takahashi H Haga Y and Suzuki T 1993 Jpn J Appl Phys Series 8
182
Joint AIRAPT-22 amp HPCJ-50 IOP PublishingJournal of Physics Conference Series 215 (2010) 012031 doi1010881742-65962151012031
4
6
4
2
0
-2
In r
14x10-3
12108642
1T (K-1
)
35
90
60
20 GPa
110
CeZn3P3
Figure 2 ln ρ as a function of inverse temperature 1T The dashed straight line represents theArrhenius law for the maximum slope range between the linear portion under various pressure
10-1
100
101
102
103
104
105
106
R (
Ω)
300250200150100500
T (K)
5 GPa
CeZn3P3
7
11
14
19
Figure 3 The temperature dependence of the electrical resistivity ρ(T ) of CeZn3P3 underpressure using DAC
Joint AIRAPT-22 amp HPCJ-50 IOP PublishingJournal of Physics Conference Series 215 (2010) 012031 doi1010881742-65962151012031
3
2000
1500
1000
500
0
Eg
(K)
2520151050
P (GPa)
CeZn3P3 cubic anvil cell diamond anvil cell
Figure 4 Pressure dependence of Eg deduced from high pressure experiments using CAC(circles) and DAC (squares)
AcknowledgementWe would like to thank Prof M Abd-Elmeguid for useful technics of the DAC This workwas partially supported by the matching fund subsidy from the Ministry of Education CultureSports Science and Technology (MEXT) of the Japanese Government and by Grant-in-Aid ForScientific Research (21340092 20102008 and 19GS0205) of Japan Society for the Promotion ofScience(JSPS)
References[1] Nientiedt Andre T and Jeitschko W 1999 J Solid State Chem 146 478[2] Hara N JPS 2008 Autumn Meeting 20pQH-10[3] Hara N and Ochiai A private communication[4] Zha C S Mao H K and Hemley R J 2000 Proc Natl Acad Sci 97 13494[5] Mori N Okayama Y Takahashi H Haga Y and Suzuki T 1993 Jpn J Appl Phys Series 8
182
Joint AIRAPT-22 amp HPCJ-50 IOP PublishingJournal of Physics Conference Series 215 (2010) 012031 doi1010881742-65962151012031
4
2000
1500
1000
500
0
Eg
(K)
2520151050
P (GPa)
CeZn3P3 cubic anvil cell diamond anvil cell
Figure 4 Pressure dependence of Eg deduced from high pressure experiments using CAC(circles) and DAC (squares)
AcknowledgementWe would like to thank Prof M Abd-Elmeguid for useful technics of the DAC This workwas partially supported by the matching fund subsidy from the Ministry of Education CultureSports Science and Technology (MEXT) of the Japanese Government and by Grant-in-Aid ForScientific Research (21340092 20102008 and 19GS0205) of Japan Society for the Promotion ofScience(JSPS)
References[1] Nientiedt Andre T and Jeitschko W 1999 J Solid State Chem 146 478[2] Hara N JPS 2008 Autumn Meeting 20pQH-10[3] Hara N and Ochiai A private communication[4] Zha C S Mao H K and Hemley R J 2000 Proc Natl Acad Sci 97 13494[5] Mori N Okayama Y Takahashi H Haga Y and Suzuki T 1993 Jpn J Appl Phys Series 8
182
Joint AIRAPT-22 amp HPCJ-50 IOP PublishingJournal of Physics Conference Series 215 (2010) 012031 doi1010881742-65962151012031
4
