P. Eggenkamp - Academia.edu (original) (raw)
Papers by P. Eggenkamp
Physica B: Condensed Matter, 1990
where the excess conductivity, t:>.a(T) = e(t _ 1)-(4-d)/2, t = T /Tc , depends on the dimensiona... more where the excess conductivity, t:>.a(T) = e(t _ 1)-(4-d)/2, t = T /Tc , depends on the dimensionality of the fluctuations, d=I,2,3 (1). aN is the 'normal' conductivity, which can be approximated by aN = (AT + B)-I. Attempts to check the applicability of the above formula to the conductivity of high-Tc superconductors have already been made (see 5,6 and references therein), indicating a difference in dimensionality of the fluctuations observed in BiSrCaCuO compounds compared to those of LaBaCuO, LaSrCuO or RBaCuO (R-Y We report on measurements of the resistivity of high quality (Bh-xPbxhSr2Ca2Cu301O+y ceramics and single crystals of the (Bil-xPbxhSr2CaCu20S+y phase. The resistivity is perfectly described by the theoretical expression for excess conductivity in the case of a two component order parameter fluctuating in two dimensions. The resistance data can be exactly fitted by one set of parameters starting from the critical temperature up to about 200 K. The temperature dependence of the resistance was measured by a standard dc four point method in an automated system. The temperature was measured with an accuracy better than 0.1 K. The samples were warmed up from liquid nitrogen to room temperature with a rate lower than 1 K/min. An example of the measured R(T) characteristics is shown in figure 1. The effects caused by the thermodynamic fluctuations of the order parameter are strongly enhanced in high-Tc superconductors due to a very small coherence volume (about 3 X 3 X 0.2nm 3 in Bi compounds connected with a hole density ofO.2/Cu per CU02 plane (4) leads to a smearing of the transition t:>.T~30-40 K). The conductivity above T c in such case should follow a simple formula
Acta Physica Polonica A, 1993
DOI to the publisher's website. • The final author version and the galley proof are versions of t... more DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:
2006 IEEE International Symposium on Power Semiconductor Devices & IC's, 2006
This paper presents a thin-layer high voltage silicon-on-Previous reports of thin-layer high volt... more This paper presents a thin-layer high voltage silicon-on-Previous reports of thin-layer high voltage LIGBT devices insulator conductivity modulated device which has been have focused on the high-side device characteristics, where it optimized for use within integrated switch mode power was demonstrated that the degradation of source-follower supply applications. The device contains a linearly-graded specific on-resistance and saturation current are much charge profile in the drift region, and the fast-switching smaller for LIGBT devices than LDMOS [1]. The improved LIGBT can be used at current densities which are at least a high-side performance of conductivity modulated lateral factor-of-two greater than the SOI LDMOS of equivalent power devices makes them an ideal choice for integration of breakdown voltage (LIGBT BVds 650V / Rsp 4 ohm mm2). A power conversion circuit topologies which include multiple device failure mechanism which occurs during shortedhigh and low-side power switches. Half-and full-bridge winding SMPS transients unique to thin-layer devices has circuit topologies which are integrated using both LIGBT been documented, and device protection circuitry has been and LDMOS active power devices are more area-efficient developed to provide a transient current limit mechanism than the LDMOS-alone implementation. More recently, within the high voltage device. The electrical characteristics LIGBT structures have been considered for low-side flyback of the protected conductivity modulated thin-layer SOI high topologies with high voltage and fast switching are obtained voltage device are comparable to state-of-the-art discrete by a complex process technology [2]. This paper presents components, and as such this process technology provides a the design and characterization of thin-layer SOI LIGBT monolithic alternative for miniaturization and integration of devices with conventional planar process technology (EZswitch mode power supply topologies. HVT), and demonstrates that the LIGBT is compelling for application in low-side integrated circuit configurations such
Physical review. B, Condensed matter, 1993
In the diluted magnetic semiconductor Sn1-xMnxTe the charge-carrier concentration p is of crucial... more In the diluted magnetic semiconductor Sn1-xMnxTe the charge-carrier concentration p is of crucial importance for the low-temperature magnetic behavior. By means of neutron-diffraction experiments, in combination with ac-susceptibility, magnetization, and specific-heat data, we show that for x=0.04 the long-range-ordered ferromagnetic state observed for p=7×1020 cm-3 gradually evolves into a spin-glass state with increasing carrier concentration. In a crystal with p=11×1020 cm-3 initially a transition to a restricted-ranged ferromagnetic order occurs when the temperature is lowered in zero field, followed by a transition to a reentrant spin-glass phase. By the application of a small magnetic field (5.0 mT) the reentrant spin-glass transition is suppressed. In a p=23×1020 cm-3 crystal a spin-glass phase is entered directly from the paramagnetic regime. The neutron-diffraction results indicate the presence of short-range ferromagnetic fluctuations in this sample. The results are discussed in the context of a Ruderman-Kittel-Kasuya-Yosida model. A three-dimensional (T,x,p) magnetic phase diagram is presented.
Physical review. B, Condensed matter, 1993
Electron paramagnetic resonance (EPR) was investigated in samples of the magnetically diluted sem... more Electron paramagnetic resonance (EPR) was investigated in samples of the magnetically diluted semiconductor Pb1-x-ySnyMnxTe in the temperature range T=1.3-100 K. The samples had compositions in the range x=0.005-0.06,y=0.12-0.72 and carrier concentrations between p=1.6×1019 and 1.4×1021 cm-3. The temperature dependence of the EPR linewidth is strongly dependent on the carrier concentration. This can be understood within the framework of the Korringa relaxation mechanism and the two-valence-band model of magnetic properties of these crystals. For samples with high carrier concentrations (ferromagnetic at low temperatures) we obtained an s-d exchange integral of Jsd=33+/-2 meV. The role of metal vacancies in the effect of electron bottleneck of the EPR is also discussed.
Physical review. B, Condensed matter, Jan 15, 1992
The Ruderman-Kittel-Kasuya-Yosida (RKKY) indirect-exchange interaction via free carriers is analy... more The Ruderman-Kittel-Kasuya-Yosida (RKKY) indirect-exchange interaction via free carriers is analyzed in the case of IV-VI semimagnetic semiconductors (diluted magnetic semiconductors). Carriers responsible for the RKKY interaction in these materials originate from the anisotropic band of heavy holes located at the Sigma point of the Brillouin zone (i.e., there are 12 equivalent valleys of this band). Both intervalley and intravalley electron processes contribute to the exchange coupling. Calculations of the RKKY exchange integral and the paramagnetic Curie temperature (FTHETA) are presented. The exchange integral is anisotropic, and its dependence on the interspin distance is significantly modified in such a way that the role of antiferromagnetic couplings is increased. As a consequence, the value of FTHETA is reduced.
Materials Science Forum, 1995
Semiconductor Science and Technology, 1993
Review of Scientific Instruments, 1991
An apparatus is described for measuring the temperature and magnetic field dependencies of the re... more An apparatus is described for measuring the temperature and magnetic field dependencies of the resistance and critical current of high-temperature superconductors. The automated setup together with a set of inserts forms a universal system allowing for fast sample selection as well as for accurate complementary measurements at temperatures from 4.2 to 300 K and in high magnetic fields up to 30 T. Design details and low resistance measuring algorithm are presented and system peformance is discussed.
Physical Review Letters, 1996
DOI to the publisher's website. • The final author version and the galley proof are versions of t... more DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:
Materials Research Bulletin, 1990
Superconducting single crystals of the compound (Bil_,Pb,)2Sr2CaCu2Os with a critical temperature... more Superconducting single crystals of the compound (Bil_,Pb,)2Sr2CaCu2Os with a critical temperature above 80 K have been synthesized using the method reported by Wang Hong et al. (1). The X-ray diffraction data do not confirm the existence of a new superconducting phase in spite of the similarity of the powder X-ray diffraction patterns to those of Ref. 1. The estimated lattice constants, a = 5.4/~, b = 5.4/~, c = 30.8 /~, and the composition are characteristic of the 80-K phase of the Bi compound family. The electrical and magnetic measurements indicate a high crystal anisotropy.
Journal of Magnetism and Magnetic Materials, 1992
We report on the low-temperature specific heat of Zn1-xCoxSe. Above 10 K a contribution from near... more We report on the low-temperature specific heat of Zn1-xCoxSe. Above 10 K a contribution from nearest-neighbor coupled Co ions is visible, whereas at lower temperatures more distant magnetic ions contribute to the specific heat. The data can be described in the extended nearest-neighbor pair approximation.
Journal of Applied Physics, 1993
ABSTRACT
Journal of Applied Physics, 1994
Europhysics Letters (EPL), 1992
Magnetization, susceptibility and specific-heat data for PbSn(Mn)Te and Sn(Mn)Te will be reported... more Magnetization, susceptibility and specific-heat data for PbSn(Mn)Te and Sn(Mn)Te will be reported for various carrier concentrations. For the first time a carrier-concentration-induced breakdown of a ferromagnetic state has been observed. Based on a simple geometrical argument, a phase diagram for this new transition in RKKY-driven systems will be derived and will be compared with the ferromagnetic-to-spin-glass transition predicted by the well-known Sherrington-Kirkpatrick model.
Chinese Physics Letters, 2005
We report on the magnetic properties of the Cr-based diluted magnetic semiconductors Zn1-xCrxSe a... more We report on the magnetic properties of the Cr-based diluted magnetic semiconductors Zn1-xCrxSe and Zn1-xCrxS (x<0.01). The specific heat was measured in the temperature range 1.5<T<10 K and in magnetic fields up to 3 T, while the magnetization was measured at 2<T<40 K and B<6 T. The magnetic behavior is neither that of Brillouin paramagnets [Mn, Co diluted magnetic semiconductors (DMS's)] nor of Van Vleck systems (Fe DMS's). It results from a strong, static Jahn-Teller (JT) distortion for the Cr ions. A simple crystal-field model, which includes the JT effect, provides an overall description of the experimental data, but some discrepancies remain.
Physical review. B, Condensed matter, 1993
In the diluted magnetic semiconductor Sn1-xMnxTe the charge-carrier concentration p is of crucial... more In the diluted magnetic semiconductor Sn1-xMnxTe the charge-carrier concentration p is of crucial importance for the low-temperature magnetic behavior. By means of neutron-diffraction experiments, in combination with ac-susceptibility, magnetization, and specific-heat data, we show that for x=0.04 the long-range-ordered ferromagnetic state observed for p=7×1020 cm-3 gradually evolves into a spin-glass state with increasing carrier concentration. In a crystal with p=11×1020 cm-3 initially a transition to a restricted-ranged ferromagnetic order occurs when the temperature is lowered in zero field, followed by a transition to a reentrant spin-glass phase. By the application of a small magnetic field (5.0 mT) the reentrant spin-glass transition is suppressed. In a p=23×1020 cm-3 crystal a spin-glass phase is entered directly from the paramagnetic regime. The neutron-diffraction results indicate the presence of short-range ferromagnetic fluctuations in this sample. The results are discussed in the context of a Ruderman-Kittel-Kasuya-Yosida model. A three-dimensional (T,x,p) magnetic phase diagram is presented.
Physica B: Condensed Matter, 1990
where the excess conductivity, t:>.a(T) = e(t _ 1)-(4-d)/2, t = T /Tc , depends on the dimensiona... more where the excess conductivity, t:>.a(T) = e(t _ 1)-(4-d)/2, t = T /Tc , depends on the dimensionality of the fluctuations, d=I,2,3 (1). aN is the 'normal' conductivity, which can be approximated by aN = (AT + B)-I. Attempts to check the applicability of the above formula to the conductivity of high-Tc superconductors have already been made (see 5,6 and references therein), indicating a difference in dimensionality of the fluctuations observed in BiSrCaCuO compounds compared to those of LaBaCuO, LaSrCuO or RBaCuO (R-Y We report on measurements of the resistivity of high quality (Bh-xPbxhSr2Ca2Cu301O+y ceramics and single crystals of the (Bil-xPbxhSr2CaCu20S+y phase. The resistivity is perfectly described by the theoretical expression for excess conductivity in the case of a two component order parameter fluctuating in two dimensions. The resistance data can be exactly fitted by one set of parameters starting from the critical temperature up to about 200 K. The temperature dependence of the resistance was measured by a standard dc four point method in an automated system. The temperature was measured with an accuracy better than 0.1 K. The samples were warmed up from liquid nitrogen to room temperature with a rate lower than 1 K/min. An example of the measured R(T) characteristics is shown in figure 1. The effects caused by the thermodynamic fluctuations of the order parameter are strongly enhanced in high-Tc superconductors due to a very small coherence volume (about 3 X 3 X 0.2nm 3 in Bi compounds connected with a hole density ofO.2/Cu per CU02 plane (4) leads to a smearing of the transition t:>.T~30-40 K). The conductivity above T c in such case should follow a simple formula
Acta Physica Polonica A, 1993
DOI to the publisher's website. • The final author version and the galley proof are versions of t... more DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:
2006 IEEE International Symposium on Power Semiconductor Devices & IC's, 2006
This paper presents a thin-layer high voltage silicon-on-Previous reports of thin-layer high volt... more This paper presents a thin-layer high voltage silicon-on-Previous reports of thin-layer high voltage LIGBT devices insulator conductivity modulated device which has been have focused on the high-side device characteristics, where it optimized for use within integrated switch mode power was demonstrated that the degradation of source-follower supply applications. The device contains a linearly-graded specific on-resistance and saturation current are much charge profile in the drift region, and the fast-switching smaller for LIGBT devices than LDMOS [1]. The improved LIGBT can be used at current densities which are at least a high-side performance of conductivity modulated lateral factor-of-two greater than the SOI LDMOS of equivalent power devices makes them an ideal choice for integration of breakdown voltage (LIGBT BVds 650V / Rsp 4 ohm mm2). A power conversion circuit topologies which include multiple device failure mechanism which occurs during shortedhigh and low-side power switches. Half-and full-bridge winding SMPS transients unique to thin-layer devices has circuit topologies which are integrated using both LIGBT been documented, and device protection circuitry has been and LDMOS active power devices are more area-efficient developed to provide a transient current limit mechanism than the LDMOS-alone implementation. More recently, within the high voltage device. The electrical characteristics LIGBT structures have been considered for low-side flyback of the protected conductivity modulated thin-layer SOI high topologies with high voltage and fast switching are obtained voltage device are comparable to state-of-the-art discrete by a complex process technology [2]. This paper presents components, and as such this process technology provides a the design and characterization of thin-layer SOI LIGBT monolithic alternative for miniaturization and integration of devices with conventional planar process technology (EZswitch mode power supply topologies. HVT), and demonstrates that the LIGBT is compelling for application in low-side integrated circuit configurations such
Physical review. B, Condensed matter, 1993
In the diluted magnetic semiconductor Sn1-xMnxTe the charge-carrier concentration p is of crucial... more In the diluted magnetic semiconductor Sn1-xMnxTe the charge-carrier concentration p is of crucial importance for the low-temperature magnetic behavior. By means of neutron-diffraction experiments, in combination with ac-susceptibility, magnetization, and specific-heat data, we show that for x=0.04 the long-range-ordered ferromagnetic state observed for p=7×1020 cm-3 gradually evolves into a spin-glass state with increasing carrier concentration. In a crystal with p=11×1020 cm-3 initially a transition to a restricted-ranged ferromagnetic order occurs when the temperature is lowered in zero field, followed by a transition to a reentrant spin-glass phase. By the application of a small magnetic field (5.0 mT) the reentrant spin-glass transition is suppressed. In a p=23×1020 cm-3 crystal a spin-glass phase is entered directly from the paramagnetic regime. The neutron-diffraction results indicate the presence of short-range ferromagnetic fluctuations in this sample. The results are discussed in the context of a Ruderman-Kittel-Kasuya-Yosida model. A three-dimensional (T,x,p) magnetic phase diagram is presented.
Physical review. B, Condensed matter, 1993
Electron paramagnetic resonance (EPR) was investigated in samples of the magnetically diluted sem... more Electron paramagnetic resonance (EPR) was investigated in samples of the magnetically diluted semiconductor Pb1-x-ySnyMnxTe in the temperature range T=1.3-100 K. The samples had compositions in the range x=0.005-0.06,y=0.12-0.72 and carrier concentrations between p=1.6×1019 and 1.4×1021 cm-3. The temperature dependence of the EPR linewidth is strongly dependent on the carrier concentration. This can be understood within the framework of the Korringa relaxation mechanism and the two-valence-band model of magnetic properties of these crystals. For samples with high carrier concentrations (ferromagnetic at low temperatures) we obtained an s-d exchange integral of Jsd=33+/-2 meV. The role of metal vacancies in the effect of electron bottleneck of the EPR is also discussed.
Physical review. B, Condensed matter, Jan 15, 1992
The Ruderman-Kittel-Kasuya-Yosida (RKKY) indirect-exchange interaction via free carriers is analy... more The Ruderman-Kittel-Kasuya-Yosida (RKKY) indirect-exchange interaction via free carriers is analyzed in the case of IV-VI semimagnetic semiconductors (diluted magnetic semiconductors). Carriers responsible for the RKKY interaction in these materials originate from the anisotropic band of heavy holes located at the Sigma point of the Brillouin zone (i.e., there are 12 equivalent valleys of this band). Both intervalley and intravalley electron processes contribute to the exchange coupling. Calculations of the RKKY exchange integral and the paramagnetic Curie temperature (FTHETA) are presented. The exchange integral is anisotropic, and its dependence on the interspin distance is significantly modified in such a way that the role of antiferromagnetic couplings is increased. As a consequence, the value of FTHETA is reduced.
Materials Science Forum, 1995
Semiconductor Science and Technology, 1993
Review of Scientific Instruments, 1991
An apparatus is described for measuring the temperature and magnetic field dependencies of the re... more An apparatus is described for measuring the temperature and magnetic field dependencies of the resistance and critical current of high-temperature superconductors. The automated setup together with a set of inserts forms a universal system allowing for fast sample selection as well as for accurate complementary measurements at temperatures from 4.2 to 300 K and in high magnetic fields up to 30 T. Design details and low resistance measuring algorithm are presented and system peformance is discussed.
Physical Review Letters, 1996
DOI to the publisher's website. • The final author version and the galley proof are versions of t... more DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:
Materials Research Bulletin, 1990
Superconducting single crystals of the compound (Bil_,Pb,)2Sr2CaCu2Os with a critical temperature... more Superconducting single crystals of the compound (Bil_,Pb,)2Sr2CaCu2Os with a critical temperature above 80 K have been synthesized using the method reported by Wang Hong et al. (1). The X-ray diffraction data do not confirm the existence of a new superconducting phase in spite of the similarity of the powder X-ray diffraction patterns to those of Ref. 1. The estimated lattice constants, a = 5.4/~, b = 5.4/~, c = 30.8 /~, and the composition are characteristic of the 80-K phase of the Bi compound family. The electrical and magnetic measurements indicate a high crystal anisotropy.
Journal of Magnetism and Magnetic Materials, 1992
We report on the low-temperature specific heat of Zn1-xCoxSe. Above 10 K a contribution from near... more We report on the low-temperature specific heat of Zn1-xCoxSe. Above 10 K a contribution from nearest-neighbor coupled Co ions is visible, whereas at lower temperatures more distant magnetic ions contribute to the specific heat. The data can be described in the extended nearest-neighbor pair approximation.
Journal of Applied Physics, 1993
ABSTRACT
Journal of Applied Physics, 1994
Europhysics Letters (EPL), 1992
Magnetization, susceptibility and specific-heat data for PbSn(Mn)Te and Sn(Mn)Te will be reported... more Magnetization, susceptibility and specific-heat data for PbSn(Mn)Te and Sn(Mn)Te will be reported for various carrier concentrations. For the first time a carrier-concentration-induced breakdown of a ferromagnetic state has been observed. Based on a simple geometrical argument, a phase diagram for this new transition in RKKY-driven systems will be derived and will be compared with the ferromagnetic-to-spin-glass transition predicted by the well-known Sherrington-Kirkpatrick model.
Chinese Physics Letters, 2005
We report on the magnetic properties of the Cr-based diluted magnetic semiconductors Zn1-xCrxSe a... more We report on the magnetic properties of the Cr-based diluted magnetic semiconductors Zn1-xCrxSe and Zn1-xCrxS (x<0.01). The specific heat was measured in the temperature range 1.5<T<10 K and in magnetic fields up to 3 T, while the magnetization was measured at 2<T<40 K and B<6 T. The magnetic behavior is neither that of Brillouin paramagnets [Mn, Co diluted magnetic semiconductors (DMS's)] nor of Van Vleck systems (Fe DMS's). It results from a strong, static Jahn-Teller (JT) distortion for the Cr ions. A simple crystal-field model, which includes the JT effect, provides an overall description of the experimental data, but some discrepancies remain.
Physical review. B, Condensed matter, 1993
In the diluted magnetic semiconductor Sn1-xMnxTe the charge-carrier concentration p is of crucial... more In the diluted magnetic semiconductor Sn1-xMnxTe the charge-carrier concentration p is of crucial importance for the low-temperature magnetic behavior. By means of neutron-diffraction experiments, in combination with ac-susceptibility, magnetization, and specific-heat data, we show that for x=0.04 the long-range-ordered ferromagnetic state observed for p=7×1020 cm-3 gradually evolves into a spin-glass state with increasing carrier concentration. In a crystal with p=11×1020 cm-3 initially a transition to a restricted-ranged ferromagnetic order occurs when the temperature is lowered in zero field, followed by a transition to a reentrant spin-glass phase. By the application of a small magnetic field (5.0 mT) the reentrant spin-glass transition is suppressed. In a p=23×1020 cm-3 crystal a spin-glass phase is entered directly from the paramagnetic regime. The neutron-diffraction results indicate the presence of short-range ferromagnetic fluctuations in this sample. The results are discussed in the context of a Ruderman-Kittel-Kasuya-Yosida model. A three-dimensional (T,x,p) magnetic phase diagram is presented.