Lok Sabha Question No. 3097 (UNSTARRED), answered on 2021-08-06
Subject: Development of Electrically Configured Nanochannels
Ministry: SCIENCE AND TECHNOLOGY
Asked by: Midhun Reddy

## MINISTRY OF SCIENCE AND TECHNOLOGY DEPARTMENT OF SCIENCE AND TECHNOLOGY

## GOVERNMENT OF INDIA LOK SABHA

UNSTARRED QUESTION No. 3097 TO BE ANSWERED ON 06/08/2021

DEVELOPMENT OF ELECTRICALLY CONFIGURED NANO-CHANNELS 3097.  SHRI P.V. MIDHUN REDDY:

Will the Minister of SCIENCE AND TECHNOLOGY ǒव£ान और Ĥौƭोिगकȧ

मंğी be pleased to state:

- (a)       whether  the  Government  has  recently  been  able  to  develop electrically configured nano-channels which can eradicate wastage of energy and bring in wave-based computing;
- (b)       if so, the details thereof;
- (c)        whether this technology has the potential to transform the onchip data communication and processing in future and if so, the details
- thereof;
- (d)      whether the nano-channels can be designed/equipped to transfer the development  of  on-chip  multiplexing  devices  in  future  based  on  the
- specific bands  of frequencies through parallel channels  for progress  achieved  so  far  in  the  field  of  spintronics  and  voltagecontrolled magnetic anisotropy; and
- (e)     if so, the details thereof along with the benefits of this technology?

## ANSWER

MINISTER OF STATE (INDEPENDENT CHARGE) OF SCIENCE AND TECHNOLOGY AND EARTH SCIENCES (DR. JITENDRA SINGH)

ǒव£ान और Ĥौƭोिगकȧ तथा पृØवी ǒव£ान क े राÏय मंğी ( èवतंğ Ĥभार) (डॉ . ǔजतɅġ िसंह)

- (a) Yes Sir. The Department of Science & Technology under its Nano Mission Programme had supported a Thematic Unit of Excellence on Nano Devices Technology in financial Year 2011-12 at SN Bose National Centre for Basic Sciences, Kolkata (SNBNCBS-K) focussing on building various Nano Devices

Technologies. Professor Anjan Barman was the Coordinator for this Unit. He had simultaneously taken an International Collaborative project with Japan under International bi-lateral scheme of DST. Professor Anjan Barman and his research group members at the SNB NCBS had collaboration with University of  Tokyo,  RIKEN  Labs  and  Hitachi  Labs,  in  Japan,  under  which  Professor Barman has developed electrically reconfigurable spin-wave nano-channels, that  has  the  potential  to  remarkably  reduce  the  energy  waste  and  lead  to wave-based computing.

- (b) Conventional electronic devices have logic circuits, that consist of a large number of transistors fabricated on the surface of a semiconductor wafer and interconnected by metallic wires. In  electronic  devices, data  is  carried  by electric  charges,  which  creates  undesirable  Joule  heating  and  limits  the integration  density.  As  an  alternative,  spintronic  devices  offer  to  harness electron  spins,  instead  of  charge.  The  ferromagnetic  materials  possess  a permanent magnetic moment as the neighbouring electronic spins get aligned parallel to each other. Perturbing one spin in a ferromagnetic material can setoff a wave, known as spin wave, due to the collective processional motion of spins. Like other waves (e.g., sound waves, light waves), the spin waves can be  employed  to  carry  an  information  encoded  in  its  amplitude,  phase, wavelength  and  frequency.  The  spin  waves  can  propagate  through  the magnetic  media  without  moving  any  charge  particles,  which  eliminates unwanted heating and offers for the development of an alternative wave-based technology. In addition to this, the transmitted data can be retained within the spins  after  transmission  without  supplying  any  external  power  thereby reducing the energy wastage. Another advantage of spin wave is that they may have much smaller wavelength as opposed to sound wave and light wave which makes them compatible with nanoscale devices.
- (c)  Yes Sir. This technology has the potential for the development of on-chip data communication and processing. The field of magnonics deals with spin waves (quanta of which is called magnons), through periodic magnetic media. It is analogous to photonics or phononics but has many advantages over the above two fields. These have lower energy consumption, easier integrability and compatibility with CMOS structure, re-programmability and reconfigurability, smaller device features, anisotropic properties, non-

reciprocity and efficient tunability by various external stimuli to name a few. It has applications in magnonic memory, logic devices, transistors, transducers, on-chip RF components (filters, attenuators, diodes, circulators, directional couplers, splitters, demultiplexers, etc.), all-magnon circuits and neuromorphic & wave-based computing.

- (d)  Yes, Sir. It is a technology for current and future challenges.
- (e)   In  this  study,  Professor  Barman  and  his  team  has  experimentally demonstrated the formation of fully reconfigurable nano-channels by applying electric field at the surface of ferromagnet for the first time. This research study will have many implications and future perspectives. The present study, can be extended, to form a number of parallel channels by applying different electric fields to each channel. In that case, each channel, can be utilized to send spin waves with a band of frequencies. This will be particularly important for  the  development  of  spin  wave  based  parallel  computing  devices.  In addition  to  that,  the  study  of  the  interaction  among  the  propagating  spin waves through nano-channels will be a subject of intense research. This will be  particularly  important  when  widths  of  the  nano-channels  and  their separations are significantly reduced to increase the integration density of devices.  The  interaction  among  spin  waves  propagating  through  nanochannels can significantly modify the spin wave band-widths and band gaps. If nano-channels are formed in two dimensions, instead of one dimension as in the present study, then the spin wave frequency bands may show complex behaviour, i.e., a number of bands with varying band width and band gap may be observed, which can even be tuned by changing widths of gate electrodes and  strength  of  applied  electric  field.  This  can  be  very  useful  to  develop various  types  of  on-chip  multiplexing  devices,  microwave  filters  (e.g.,  low pass,  band  pass),  attenuators  for  future  applications.  Overall,  the  current research  opens  up  the  possibilities  of  many  future  studies  and  potential applications.

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