Search query: insulator  ppms

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abstract: We have designed and developed an experimental setup to measure the Seebeck coefficient of a variety of samples at cryogenic temperatures and under magnetic fields up to 7 T employing the physical property measurement system (PPMS) The measurement technique uses a low frequency ac thermal gradient generated by two thin film heaters in thermal contact with the sample. Heaters and temperature sensors are all fitted on a standard PPMS sample puck. The validity of this method is tested by measuring the thermoelectric power of several superconductors and thermoelectric samples. We have used this technique to measure the thermoelectric power of various topological insulator single crystals (Pb0.8Sn0.2Te, Bi2Te3, Bi2Se2.1Te0.9, and Sb2Te3) The developed hardware and software control is suitable for studying the thermoelectric power of small samples (length 2 mm) in a commercial cryomagnetic system (PPMS) and it allows for studying superconductor, semiconductor, thermoelectric, or topological insulator material in wide temperature (2 300 K) and magnetic field (0 7 T) ranges.
author_names: Keshav Shrestha

Melissa Gooch

Bernd Lorenz

Ching-Wu Chu
title: Experimental Setup of Ac Thermoelectric Power Measurements in a Cryocooler PPMS System and Its Implementation to Superconductors, Topological Insulator, and Thermoelectric Materials
venue: Instruments and Experimental Techniques
year: 2019

abstract: Abstract A long range magnetic order in the topological insulator (Bi2Te3) achieved a great interest by the doping of magnetic elements on to Bi and Te sites. The magnetic moments can be introduced by adding trivalent rare earth elements such as Ce and I. In this report, Bi2Te3, Ce0.2Bi1.8Te3, and Ce0.2Bi1.8Te2.9I0.1 nanoparticle were synthesized by the novel low temperature double solvent sol gel technique. The co doped nanoparticles were characterized by X ray diffraction (XRD) field emission scanning electron microscopy (FESEM) high resolution transmission electron microscopy (HRTEM) physical properties measurement system (PPMS) and vibrating sample measurement system (VSM) The VSM studies showed that the magnetization (M) of pure Bi2Te3 sample was successfully increased by adding iodine onto the Ce doped sample (Ce0.2Bi1.8Te2.9I0.1) For in depth analysis, PPMS results revealed that the as synthesized samples exhibit paramagnetic nature which then exchange into antiferromagnetic behavior after substituting Ce I onto Bi2Te3, at a varying temperature range from 0 to 400 K. The density functional theory (DFT) was also performed to understand the exchange biased phenomenon for as synthesized samples. Moreover, the experimental results can predict that the magnetic samples synthesized by the novel double solvent sol gel method can provide magnetic materials with large remnant magnetization compared with the pure Bi2Te3.
author_names: Syed Irfan

Jingting Luo

Fan Ping

Zheng Zhuanghao
title: Theoretical and experimental investigation of magnetic properties of iodine and cerium Co doped Bi2Te3 nanoparticles
year: 2020

abstract: Abstract In this work we investigate the growth and magnetotransport properties of Co doped topological insulator Bi2Te3 deposited on Si(1 1 1) substrates by means of DC magnetron sputtering. The structure and morphology of the films were studied using X Ray Diffraction (XRD) Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscopy (AFM) Magnetotransport measurements were performed with a Physical Property Measurement System (PPMS) The pristine samples have a metallic behavior while the Co doped are semiconductors. The magnetoresistance curves exhibit a sharp cusp for temperatures below 20 K that correspond to weak antilocalization phenomena and are analysed using the Hikami Larkin Nagaoka model. The WAL phenomenon vanishes with temperature increase due to electron phonon scattering. The doped samples present an ambipolar transport with a change in the sign of the dominant carriers with temperature.
author_names: A Pilidi

Th Speliotis

George Litsardakis
title: Structural and magnetotransport characterization of magnetron sputtered co doped Bi2Te3 thin films
year: 2020

abstract: Abstract We carried out a systematic study on the effect of the substitution of Ti2+ and Ru4+ ions for Fe3+ ions on the structural and magnetic properties of the strontium ferrite SrFe12 2xRuxTixO19 nanoparticles with 0 x 0.3 using x ray diffraction, Quantum Design PPMS 9 magnetometry, and electrical resistivity. A clear irreversibility between the zero field cooled and field cooled curves was observed below room temperature and the zero field cooled magnetization curves displayed a broad peak at a temperature TM. These results were discussed within the framework of random particle assembly model and associated with the magnetic domain wall motion. The resistivity data showed some kind of a transition from insulator to perfect insulator around T M The high temperature magnetization measurements exhibited sharp peaks just below Tc indicating a superparamagnetic behavior. With Ru Ti substitution, the saturation magnetization at 5 K showed small variations were it slightly increased with increasing x up to 0.2, and then decrease for x 0.3, while the coercivity decreased monotonically, recording a reduction of about 78% at x 0.3. These results were discussed in light of the cationic distributions based on the results of the structural refinements.
author_names: Abdel Khaleq Mousa Alsmadi

Ibrahim Bsoul

Sami H Mahmood

G A Alna'washi

Feras M O Al-Dweri

Yazan Maswadeh

Ulrich Welp
title: Magnetic study of M type Ru Ti doped strontium hexaferrite nanocrystalline particles
year: 2015

abstract: We introduce the marriage of two technologies: digital microfluidics (DMF) a technique in which droplets are manipulated by application of electrostatic forces on an array of electrodes coated by an insulator, and porous polymer monoliths (PPMs) a class of materials that is popular for use for solid phase extraction and chromatography. In this work, circular PPM discs were formed in situ by dispensing and manipulating droplets of monomer solutions to designated spots on a DMF device followed by UV initiated polymerization. We used PPM discs formed in this manner to develop a digital microfluidic solid phase extraction (DMF SPE) method, in which PPM discs are activated and equilibrated, samples are loaded, PPM discs are washed, and the samples are eluted, all using microliter droplets of samples and reagents. The new method has extraction efficiency (93% comparable to that of pipet based ZipTips and is compatible with preparative sample extraction and recovery for on chip desalting, removal of surfactants, and preconcentration. We anticipate that DMF SPE may be useful for a wide range of applications requiring preparative sample cleanup and concentration.
author_names: Hao Yang

Jared M Mudrik

Mais J Jebrail

Aaron R Wheeler
title: A digital microfluidic method for in situ formation of porous polymer monoliths with application to solid phase extraction.
venue: Analytical chemistry
year: 2011

abstract: Surface plasmon polaritons (SPPs) are surface charge density oscillations localized to a metal dielectric interface. In addition to being considered as promising candidates for a variety of applications, structures that support SPPs, including metal insulator metal (MIM) multilayers, are of fundamental interest because of the variety of collective plasmonic modes they support. Previously, a particular class of "forbidden" plasmon polariton modes (PPMs) was proposed that includes plasmon polariton modes confined to a region of dispersion space not typically accessible to surface constructed collective excitations. Specifically, for these modes, known as Guided Wave PPMs (GW PPMs) due to the dielectric asymmetry of the central layer, the solution to the wave equation in the center insulator layer is oscillatory while remaining surface bound both to the supporting substrate and the exposed surface. These modes are supported by a simple physical structure that results from a minor symmetry modification of the traditional MIM structure, specifically the use of a central insulator layer with a higher refractive index than the supporting substrate. However, they display fundamental properties that are distinctly different from those of standard SPPs and from recently reported hybrid plasmonic modes. While GW PPMs have been explored theoretically, they have not yet been realized experimentally. In this article, we present the first experimental demonstration of GW PPMs. Specifically, we excite and detect GW PPMs at visible frequencies and match model predictions to experimental results with remarkable accuracy using minimal parameter fitting. In addition to the experimental detection, we calculate and report on other interesting and relevant features of the detected modes, including the associated electric field profiles, confinement values, and propagation lengths, and discuss in terms of the applications relevance of GW PPMs.Surface plasmon polaritons (SPPs) are surface charge density oscillations localized to a metal dielectric interface. In addition to being considered as promising candidates for a variety of applications, structures that support SPPs, including metal insulator metal (MIM) multilayers, are of fundamental interest because of the variety of collective plasmonic modes they support. Previously, a particular class of "forbidden" plasmon polariton modes (PPMs) was proposed that includes plasmon polariton modes confined to a region of dispersion space not typically accessible to surface constructed collective excitations. Specifically, for these modes, known as Guided Wave PPMs (GW PPMs) due to the dielectric asymmetry of the central layer, the solution to the wave equation in the center insulator layer is oscillatory while remaining surface bound both to the supporting substrate and the exposed surface. These mode.
author_names: Rachel C Owen

Kodiak S Murphy

Kyle Hoke

Trevor James Morgan

Brad L Johnson

Janelle M Leger
title: Detection of guided wave plasmon polariton modes in a high index dielectric MIM structure
year: 2017

abstract: The processing, microstructures and properties of La0.7Sr0.3Mn1 xZnxO3 perovskite manganite, with x=0, 0.1, 0.2, and 0.3 have been investigated. X ray diffraction, scanning electron microscopy (SEM) and other characterisation methods were used to study the relations of microstructure and properties. The X ray powder diffraction results show a single phase for the 0<<em>x<0.3 region that confirms the zinc incorporation into the Mn site. The SEM images with magnification 1500x indicate that the studied system is a single phase. The transport measurements show decreasing of insulator to metal transition temperature, Tt, with increasing the zinc concentration on the Mn site, while the resistivity increases with increasing the zinc doping level for 0<<em>x<0.1. The maximum resistivities are found at 380 and 160 K, respectively. The PPMS measurements show that the magnetisation value is greatest for x=0.1 and drastically decrease for the parent material, as well as with increasing the zinc doping concentration above 20% when the compound changes from ferromagnetic to paramagnetic. The paramagnetic to ferromagnetic transition temperature variations, Tc, agrees with the insulator to metal variations, Tt, from the transport measurements for the parent and 10% doped material. For zinc doping levels above 20% the behavior of the studied system changes from ferromagnetic to paramagnetic.
author_names: Emilia Velinova Sotirova-Haralambeva

Xio Lin Wang

K H Liu

T M Silver

Konstantin Konstantinov

Joseph Horvat
title: Zinc doping effects on the structure transport and magnetic properties of La 0 7 Sr 0 3 Mn 1 2 x Zn x O 3 manganite oxide
year: 2017

abstract: The positron annihilation techniques and X ray diffraction have been used to study the microstructure of the La0.67Ca0.33MnO3 ceramics prepared by the solid state reaction method at different sintered temperatures (T=1573K, 1623K, 1673K, 1723K, 1773K, 1823K) And the electro magnetic transport behavior of the samples was measured by VSM and Resistivity modular on PPMS. According to these results, all samples show a perovskite structure, the ferromagnetic paramagnetic and metal insulator transitions occur at the transition temperature Tc and TMI, respectively, which is almost the same. For La0.67Ca0.33MnO3 sintered at 1673K, the mean positron lifetime is the largest, the maximum value of the magnetization is achieved on the magnetization temperature curve at H=0.2mT, while the transition temperature occurs at about 244K.
author_names: Shoulei Xu

Er Juan Xie

Xiu Cao

Yu Yang Huang

Dingkang Xiong

Wen Deng
title: Studies of Microstructure and Electro Magnetic Transport Property of La0.67Ca0.33MnO3 Ceramic
year: 2017

abstract: We have successfully measured physical and magnetic properties of the La0.5Ca0.5Mn0.9Cu0.1O3 at temperature in the range of 10 100 K. Physical properties have covered electrical resistivity and specific heat. The properties, which serve as a function of temperature, were investigated by using Physics Properties Measurement System (PPMS) with and without an external magnetic field up to 8.5 Tesla. The magnetic structure was characterized using High Resolution Powder Diffraction (HRPD) at room and low temperatures. Furthermore, the magnetization was measured by using Magnetic Properties Measurement System (MPMS) with the external magnetic field of 0 7 Tesla. In the temperature interval of 10 53 K, the resistivity of the sample increased with the increasing of external magnetic field. At temperatures T 53 K, the samples were crystalline metal. This was revealed by fitting the graph Ln R as a function of 1/T. At temperatures T 53 K, the sample was an insulator according to fittings Ln R as a function of 1/T 0.25 The result was also shown by the decreasing value of the resistivity of the sample. The transition temperature of the metal insulator (TMI) decreased with the increasing of external magnetic field, i.e. from 60 K without an external magnetic field to 53 K with external magnetic field 8.5 Tesla. A coefficient electron specific heat and specific heat of spin wave increased, and phonon specific heat was relatively unchanged in the presence of an external magnetic field. Results of HRPD experiment were analyzed by using Fullprof program. At room temperature, the sample had the paramagnetic phase, while at low temperatures of 20 K it had antiferromagnetic phase. Temperature phase transition from the paramagnetic to antiferromagnetic phase or Neel temperature was around 225 K. However, the saturation magnetization of the sample was not observed.
author_names: Yohanes Edi Gunanto

Wisnu Ari Adi

Eden Steven

Budhy Kurniawan

Takayuki Ono

H K Tanaka
title: Physical and Magnetic Properties of La 0 5 Ca 0 5 Mn 0 9 Cu 0 1 O 3 at Temperature in the Range of 10 100
year: 2017

abstract: An inorganically template metaphosphoric acid containing copper salt, nanomaterial, has been synthesized and characterized with different measurement techniques such as Differential Scanning Calorimeter (DSC) UV Vis NIR, HRTEM, VSM, PPMS and X RD. The thermal property of this salt has been studied at a low temperature up to 223 K from 298 K with DSC. The specific heat capacity of this complex has been measured in atmospheric O2 at a rate of 10 K min 1 from 298 K to 223 K and vice versa in two thermal cycles. The net specific heat capacity of this salt is found 88.28 J/gm.K and 86.56 J/gm.K in first and second thermal cycles, respectively. There is a discontinuity in the specific heat at 106 s while measuring the specific heat capacity of the above nanomaterial at constant temperature 283 K. This particle size of this nanomaterial is 10 nm. The paramagnetic Curie temperature (thP) and Curie constant (C) are 18.29 K and 1.35x10 3 respectively. This material founds insulator from PPMS and UV Vis NIR mea.
author_names: Trilochan Swain

Gouri Sankhar Brahma
title: Low temperature property of Metaphosphatecopper(II/I) salt
year: 2016