Vivas Bagwe - 09.07.2010

1. System Setups,a. Fabrication of Low Temperature STM CG24,b. Fabrication of He3 STM-500 mK - 8T - CG30.

2. Growth & Characterization of Thin Films, &3. Other responsibilities.

Plan of talk

1. System Setup : Scanning Tunneling Microscopy Lab

Setup in 2005-06

Base Temperature – 2.6 KNoise in the Currrent (engaged position) <1 pATopography Noise <10 pMDisplacement Vibrational Analysis <70pM

In-Situ Growth of Sample possible.

Single crystal of FeSe0.5Te0.5

Sputtered Au image at room temperature obtained using W tip; bias=100mV; Iset =100pA

1.The Outer Sound & RF Proof Room

A 60 mm thick PUF panel with 2 mm thick GI sheets on both sides.Foam acts as a sound barrier whereas the GI provides shielding from other frequencies mainly RF. The whole room is grounded to a separate ground. This eliminates electrical noise from other systems.Room is divided in 2 portions, outer room for electronics and the User/Controller , about 30 Sq. Ft., & The inner room for Actual Setup about 20 Sq. Ft.Panels provided and erected by Polfrost Pvt. Ltd.

1.The Outer Sound & RF Proof Room,2.The Concrete Structure (Passive Isolation),3.The Active Isolators .

To Isolate : Building Noise ~ 1.25 to 1.5 Hz & Ground Vibrations Seismic activity, Subway, road and rail systems, Industrial metalworking facilitiesConstruction equipment upto 2000HzElectromagnetic Noise

Separate Pillar for Split A/C

Double walled glass window

2.The Concrete Structure (Passive Isolation),

TOP VIEW

4*4 feet deep Pit was dug in the ground.

Total weight the top plate can take is ~300 Kgs

2.The Concrete Structure (Passive Isolation),

Cross Sectional view

Vibration isolation units

Cryostat

STM Head

Sample manipulatorsSputteringchamber

Its been a year since good data is being produced. Anand Kamlapure and Dr. Pratap

Fabrication of He3 STM-500 mK - 8T - CG30.

Sourced from Janis Inc.: Setup in 2008-09

Smart Table

Different approach for vibration damping as the whole system now rests on the ground floor. Luckily Newport ‘s Smart Table came to a good use. The Pneumatic legs act as passive isolators and the Smart Table damps out higher frequencies. (yet to check with Vibration Analysers)Table can handle upto 1 ton of weight. New chamber etc can be added. Sufficient Dead weight can be added to provide more effective damping if needed.More focus on Sound Damping –Use of Gypsum Board– Perforated boards cut out Standing waves providing effective isolation.

Gypsum board

Further Work of testing and Insert Fabrication going on: Garima Saraswat & Dr. Pratap

Growth & Characterization of Films1. Growth of Thin Films by Sputtering 2. Thickness profiling by the old DEKTAK and now the New AMBIOS profilometer.3. Topography by AFM- Veeco DI 3A contact mode4. XRAY Diffraction – PHI Scan measurements on PANALYTICAL. (Mahesh Gokhale)5. TEM – TECNAI and Titan (Rudheer Bapat, Bhagyashree Chalke & S. C. Purandare)

TEM Sample Preparation.It requires Electron Transparent Samples ~ 100 – 200 nm thick.

For Plane view:1.A 3 mm disc is first cut out from the sample by an ultrasonic disc cutter.2.This disc is then pasted on the Grinder Base and lapped on various polish papers i.e 40 , 15 and 5 microns till the sample is about 120 microns in thickness.3.This sample is then put on the Dimpler and a dimple or a pit is formed in its center which is about 30 microns thick. Diamond/Graphite paste is used with the Phosphor-Bronze dimpling disc. Later on the sample is further polished to 10 microns with a cloth disc and Alumina powder .4.This dimpled sample is then put in a Ion Polisher which is used to form a hole in the center of the dimple. The areas around that hole are around 100-200 nm thick. For a cross sectional sample :1.The sample is first cleaved in half and pasted with the substrate sides out. This sandwich is then polished to about 0.3 mm * 0.7 mm * 5 mm and put in a steel or moly tube of diameter 3 mm and cured with a glue.2.This Tube with the sample is then cut into small slices with the help of a diamond saw, measuring around 500 microns thick. All the above steps from 2 onwards are repeated.

The sample thus prepared is put on a special holder and then taken for TEM Analysis.Since it is a destructive type of sample preparation technique, great care has to be taken at each Step.

4. Other Responsibilities

1. Fire in CG24 in 2007 – Cleaning and Renovation of Lab &Salvage of Equipments.

2. Salvage and Disposal of equipment in D329 and erection of a New Clean Room.

3. Replication of Vibration Damping System In Dr. Mandar’s Lab Cg29.4. Office renovation in C342.5. Donations of Instruments to VIIT Pune, NIT Kochi and IGCAR Kalpakkam.6. IVW10- 2005 & TWIM-2006 Registration desk, Transport, Designing of Abstract book and other

contents and Full Design of Conference CD.7. Inventory & Transfer / Salvage of equipment Control in the Lab, &8. General Maintenance of Labs and Handling of all Purchase related Matters. (From Oct 2005—145 files have been processed)

Thank-you

Dr.Pratap RaychaudhuriSubhash Pai,John Jesudasan, Sanjeev, Madhavi,

Anand, Mintu and Garima.

1. System Setup : Sputtering Unit

Sourced from Excel Instruments : Setup in 2004

1. DC and RF Sputtering Possible2. Provision for 3 guns – Co-Sputtering Possible

2. Growth of Thin Films

Mainly by Sputtering:

Cobalt – Goutam & Swati for the spin polarisation work Madam Palkar for coating of MFM tips S.C. Purandare for checking the effect of thickness on domain sizes & Dr. Prajapat (BARC) and Ashok Mohapatra Niobium - Madhavi Chand for the summer project – Lithographic point contactCopperGoldPlatinumAluminium – Dr. Sanjeev Kumar (Uni.Hyd) - for Tunnel junction workTantalum – Prof. SVK. Kumar – On Silicon and Gold substrates. – to isolate a single DNA strand

By PLD

LaEuSrMnO films for Dr. Rakesh Kumar – Prof.Paulose – At various Oxygen pressures.

Some AFM Images

20 50 100 150 250 microns

Some PublicationsBandwidth control effects in electron doped manganite La0.7-xYxCe0.3MnO3

Kavita Bajaj1, 2, Vivas Bagwe1, John Jesudasan1, Pratap Raychaudhuri*

Solid State Communications Volume 138, Issues 10-11 , June 2006, Pages 549-552 Swift-Heavy-Ion-irradiation induced enhancement in conductivity of Chemical Solution Deposited La0.7Ba0.3MnO3 thin films.R. N. Parmar, J. H. Markna, and D. G. Kuberkar, Ravi Kumar, D. S. Rana, Vivas C. Bagwe and S. K. Malik ,APL 89,202506 (2006) Superconducting properties and Hall effect of epitaxial NbN thin filmsS. P. Chockalingam et.al. PRB 77, 214503 _2008 Tunneling studies in a homogeneously disordered s-wave superconductor: NbNS. P. Chockalingam et.al PRB 79, 094509 _2009. Competing effects of surface phonon softening and quantum size effects on thesuperconducting properties of nanostructured PbSangita Bose et.el J. Phys.: Condens. Matter 21 (2009) 205702 Formation of nanocrystalline TiO2 by 100 MeV Au8+Madhavi Thakurdesai et.al., Applied Surface Science 255 (2009) 8935–8940

Electroresistive effects in electron doped manganite La0.7Ce0.3MnO3 thin films.Kavita Bajaj, John Jesudasan, Vivas Bagwe, D.C. Kothari & P Raychaudhuri J. Phys.: Condens. Matter 19 (2007) 046208 (7pp).

Common Vibration Sources

EXTERNAL SOURCESSeismic activitySubway, road and rail systemsIndustrial metalworking facilitiesConstruction equipmentWind

INTERNAL SOURCESHVAC equipmentElevator and conveyance systemsFluid pumping equipmentAerobics and exercise roomsCommon Vibration ImpactsHuman annoyanceStructural fatigueDisturbance of sensitive equipment(Scanning Electron Microscopes, Nuclear Magnetic Resonance equipment, Coordinate centering equipment)

1. System Setup : Relocation of CF cryostat and He3 cryostat.

Equipment from Lab D328 was also shifted to Cg24 and the lab was converted to the Clean room ante chamber