Quantum Transport in Thin Film Heterostructures

Quantum Transport in Thin Film Heterostructures

With the demand for development of smaller and smaller devices with higher speed, thin films science and technology plays an important role for future giga scale integration (GSI) technology.Thin films are of great importance since they exhibit novel behaviours due to its reduced dimensionality.

Therefore, knowledge and determination of the nature, functions and new properties of thin films is a direct route to develop new technologies for future applications which is further integrated with heterostructures to enhance their functionality. Such heterostructures are fabricated using various techniques such as pulsed laser deposition, ultra high vacuum dc-and rf-magnetron sputtering etc.

With the expertise in deposition of thin films/heterostructures by different deposition techniques and its characterization, our group is involved in fabrication & investigation of variety of thin films that are of technological importance. Following activities are being taken care in this group:

Activities:
People:

Scientists:

Dr. Hari Krishna Singh
Ms. Manju Singh
Dr(Ms.) Anjana Dogra
Dr. Rajib Kumar Rakshit
Dr. R.P. Aloysis
Dr. Ajeet Kumar
Dr. Parveen Kumar Siwach
Dr. Sangeeta Sahoo
Dr. Jiji Thomas Joseph Pulikkotil

 

hks65@nplindia.org
singhm@nplindia.org
anjanad@nplindia.org
rakshitrk@nplindia.org



sahoos@nplindia.ernet.in

Technical Support :

Fahimuddin

Quantum Electrical Metrology

  • National primary standard of resistance based on the integer quantum Hall effect (IQHE) is maintained to provide traceability to the industry.
  • Direct current comparator (DCC) bridge is used to directly measure 1 k W standard resistors against the quantized value.
  • Cryogenic current comparator (CCC) bridge is used to directly measure 100 W standard resistors
  • Standard resistors (1 W – 100 k W ) are measured against the 100 W /1k W using the ratio 10/100.

Quantum Hall Effect in a GaAs-AlGaAs heterostructure device measured at T=1.3 K. The inset shows the device with contacts mounted on a 12 pin To8 holder.

Strongly Correlated System- Doped Rare Earth Manganites


• Growth and Magneto transport in strongly correlated oxide thin films and multilayers. • Growth and transport in ultrathin graphitic films. • Growth and characterization of exotic low dimensional systems.
 



Impact of post deposition oxygen annealing on the surface and structural characteristics of a 36 nm thin film of Sm 0.53-x Nd x Sr 0.47 MnO 3 (x~0.1). These films were deposited on LaAlO 3 (001) substrate by DC magnetron sputtering ((Top). Magnetic field induced first order phase transition in the oxygen annealed films (Bottom)

Transition Metal Oxide Heterostructures

• Transition metal oxide heterostructures remain a strong candidate of research pertaining to their interesting physical properties such as photoconductivity,
superconductivity and co-existence of magnetism and superconductivity.

• Focus is on engineering the thin film heterostructures of pure and doped LaAlO 3 /SrTiO 3 and LaTiO 3 /SrTiO 3 using Pulsed Laser deposition (PLD) using in-situ reflection high-energy diffraction (RHEED) gun that allows to monitor atomic layer-by-atomic layer growth of epitaxial film.

• Focus is also on the theoretical calculations of electronic states and its interplay with various properties of transition metal interfaces using Density Function Theory (DFT).



50 Hz KrF excimer lasers (Energy ~ 700 mJ, ? =248nm) equipped with oxide RHEED- PLD chamber

Superconducting – Ferromagnetic Heterostructures


Spintronics integrating the relation between charge and spin of the electron provides several advantages such as non-volatile memory, increased storage density with low power consumption, thus has been a promising candidate for the next generation device applications.

• Our group employs a wide range of thin film and nano-device fabrication technologies including multi chamber deposition facility which consists of a pulsed laser, a dc-and rf-magnetron sputtering and a thermal evaporation chamber coupled in series with various facilities involving - v in-situ sample transfer facility v load lock chamber for sample loading and shadow mask mounting v DC and RF Sputtering chambers equipped with variable distance UHV compatible sputtering sources v In addition, we use multi-probe system to gain insights into various electrical transport studies.

• Fabrication of various thin-film heterostructures and devices, including Josephson junctions, superconducting single photon detector utilizing elemental as well as nitride superconductors such as Nb, NbN, VN .

Multichamber System equipped with in-situ growth by PLD, DC & RF Sputtering

•Utilizing pulse laser deposition technique for development of various magnetic tunnel junctions(MTJ) using magnetic alloys such as Co2MnSi, Co2FeSi, CoFeB and also Elemental ferromagnets such as Co, Fe etc.

Nano SQUIDS & Quantum Phase Slip

• Our main objectives are,

• The fabrication of very high quality Nb and Nb 3 Ge based superconductors for nano and micro SQUID applications aiming at the resolution of single spin detection limit and also to study the effect of quantum fluctuations on superconductivity for very thin (~ 10 nm) superconducting nanowires.

• Fabrication of Nb x Gd 1-x based composite structures/devices for the study of their magnetic and electronic properties, phase transition as a function of x.

• Quantum transport studies through superconducting and spintronic devices at low temperature in milli-Kelvin range.
UHV magnetron -sputtering unit

Currently we employ an Ultra High Vacuum (UHV) Magnetron Sputtering unit for the deposition of superconducting and magnetic thin films and the unit is equipped with v .

A load-lock chamber for sample transferring to the UHV chamber v

Two sputter guns attached to the load-lock for the fabrication of oxide based tunnel junctions. v

Three sputter guns connected to the UHV chamber for co-sputtering simultaneously.
 
   
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