Microwave Oscillators and Detectors
Based on Magnetic Tunnel Junctions
P. K. Muduli, Raghav Sharma, Dhananjay Tiwari, Naveen Sisodia,
Afshin Houshang, O. G. Heinonen, and Johan Åkerman
Abstract A nanopillar of a magnetic tunnel junction (MTJ) consisting of two magnetic layers (free and fixed) separated by an oxide barrier can be used as a microwave
generator, and also as a microwave detector, by using the concept of spin-transfer
torque. When the MTJ nanopillar is used as a microwave generator, the device is
known as a spin-torque nano-oscillator (STNO) and offers advantages of high output power over metallic-based STNOs. We first discuss the bias dependence of spin
torque and, in particular, the field-like torque present in these devices. We then discuss
the mechanism governing linewidth broadening and show how multimode excitation
and mode-hopping can affect the phase noise in these STNOs. The potential of these
oscillators for communication applications is discussed, with the focus on the synchronization and modulation of the MTJ-STNOs with an external signal. Finally the
application of these devices as microwave detectors is discussed, and we concentrate
on approaches for enhancing their microwave sensitivity.
The original version of this chapter was revised: This chapter was revised with the missed out
corrections. The correction to this chapter is available at https://doi.org/10.1007/978-981-15-69128_14
P. K. Muduli (B) · R. Sharma · D. Tiwari · N. Sisodia
Department of Physics, Indian Institute of Technology, Hauz Khas, New Delhi 110016, India
e-mail: muduli@physics.iitd.ac.in
O. G. Heinonen
Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
e-mail: heinonen@anl.gov
A. Houshang · J. Åkerman
Department of Physics, University of Gothenburg, Gothenburg 412 96, Sweden
e-mail: johan.akerman@physics.gu.se
NanOsc AB, Electrum 205, Kista 164 40, Sweden
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021,
corrected publication 2021
W. S. Lew et al. (eds.), Emerging Non-volatile Memory Technologies,
https://doi.org/10.1007/978-981-15-6912-8_1
3
Based on Magnetic Tunnel Junctions
P. K. Muduli, Raghav Sharma, Dhananjay Tiwari, Naveen Sisodia,
Afshin Houshang, O. G. Heinonen, and Johan Åkerman
Abstract A nanopillar of a magnetic tunnel junction (MTJ) consisting of two magnetic layers (free and fixed) separated by an oxide barrier can be used as a microwave
generator, and also as a microwave detector, by using the concept of spin-transfer
torque. When the MTJ nanopillar is used as a microwave generator, the device is
known as a spin-torque nano-oscillator (STNO) and offers advantages of high output power over metallic-based STNOs. We first discuss the bias dependence of spin
torque and, in particular, the field-like torque present in these devices. We then discuss
the mechanism governing linewidth broadening and show how multimode excitation
and mode-hopping can affect the phase noise in these STNOs. The potential of these
oscillators for communication applications is discussed, with the focus on the synchronization and modulation of the MTJ-STNOs with an external signal. Finally the
application of these devices as microwave detectors is discussed, and we concentrate
on approaches for enhancing their microwave sensitivity.
The original version of this chapter was revised: This chapter was revised with the missed out
corrections. The correction to this chapter is available at https://doi.org/10.1007/978-981-15-69128_14
P. K. Muduli (B) · R. Sharma · D. Tiwari · N. Sisodia
Department of Physics, Indian Institute of Technology, Hauz Khas, New Delhi 110016, India
e-mail: muduli@physics.iitd.ac.in
O. G. Heinonen
Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
e-mail: heinonen@anl.gov
A. Houshang · J. Åkerman
Department of Physics, University of Gothenburg, Gothenburg 412 96, Sweden
e-mail: johan.akerman@physics.gu.se
NanOsc AB, Electrum 205, Kista 164 40, Sweden
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021,
corrected publication 2021
W. S. Lew et al. (eds.), Emerging Non-volatile Memory Technologies,
https://doi.org/10.1007/978-981-15-6912-8_1
3