38
P. K. Muduli et al.
Table 1 Summary of sensitivity and detection frequency values from literature
Study
Geometry
Technique
Sensitivity
(mV/mW)
Frequency
(GHz)
Tulapurkar et al. [31]
ip-MTJ
STT
0.4
5–10
Tiwari et al. [133]
ip-MTJ
STT+PS
16
8–9
Jenkins et al. [163]
ip-MTJ
Vortex
Expulsion
40,000
∼ 0.1–0.2
Tsunegi et al. [143]
ip-MTJ
Vortex
Expulsion
80,000
∼ 0.45
Zhu et al. [34]
p-MTJ
VCMA+STT
440
∼1.1
Shiota et al. [157]
p-MTJ
VCMA+nlFMR
300
2
Frankowski et al. [160]
p-MTJ
VCMA
>10 4
∼1
Miwa et al. [35]
p-MTJ
VCMA+nlFMR
12,000
1.5–2
Fang et al. [36]
p-MTJ
VCMA+IL
75,400
1–1.4
Zhang et al. [161]
p-MTJ
VCMA+IL
2.1 × 10 5
∼1
Sisodia et al. [162]
p-MTJ
VCMA+PS
> 10 5
4–6
ip-MTJ in-plane magnetic tunnel junction; p-MTJ perpendicular magnetic tunnel junction; STT spin
transfer torque; PS parametric synchronization; VCMA voltage controlled magnetic anisotropy; nlFMR non-linear ferromagnetic resonance; IL injection locking
layer to spin-polarize the charge current. With the recent emergence of the spin Hall
effect, a new type of spintronic oscillator, the SHNO, has been developed [172]. This
provides a new route for the development of microwave and magnonic devices [173].
SHNOs exhibit several advantages over STNOs, including easier nano-fabrication
[174–176], lower threshold current, direct optical access to the magnetodynamically
active area [177–179], smaller and voltage tunable radiation losses [180, 181], and
suppressed nonlinear damping process [173]. While the linewidth of single SHNOs
is of the same order as that of STNOs, and their output power is currently lower
than that of STNOs, they can be mutually synchronized in both long chains and
large two-dimensional arrays, such that record high signal quality factors of 170,000
can be achieved [182, 183]. SHNOs hence offer an opportunity to implement novel
nanoscale microwave sources and emitters for wireless communications, nonlinear
frequency modulation, and magnonics applications [184–186]. For further details of
SHNO developments, issues, challenges, and application, we refer the reader to a
recent review article [15].
11 Summary and Outlook
In summary, MTJ-based STNOs are detectors continue to hold promise for applications, due to their high microwave power output and higher frequency tunability. In
P. K. Muduli et al.
Table 1 Summary of sensitivity and detection frequency values from literature
Study
Geometry
Technique
Sensitivity
(mV/mW)
Frequency
(GHz)
Tulapurkar et al. [31]
ip-MTJ
STT
0.4
5–10
Tiwari et al. [133]
ip-MTJ
STT+PS
16
8–9
Jenkins et al. [163]
ip-MTJ
Vortex
Expulsion
40,000
∼ 0.1–0.2
Tsunegi et al. [143]
ip-MTJ
Vortex
Expulsion
80,000
∼ 0.45
Zhu et al. [34]
p-MTJ
VCMA+STT
440
∼1.1
Shiota et al. [157]
p-MTJ
VCMA+nlFMR
300
2
Frankowski et al. [160]
p-MTJ
VCMA
>10 4
∼1
Miwa et al. [35]
p-MTJ
VCMA+nlFMR
12,000
1.5–2
Fang et al. [36]
p-MTJ
VCMA+IL
75,400
1–1.4
Zhang et al. [161]
p-MTJ
VCMA+IL
2.1 × 10 5
∼1
Sisodia et al. [162]
p-MTJ
VCMA+PS
> 10 5
4–6
ip-MTJ in-plane magnetic tunnel junction; p-MTJ perpendicular magnetic tunnel junction; STT spin
transfer torque; PS parametric synchronization; VCMA voltage controlled magnetic anisotropy; nlFMR non-linear ferromagnetic resonance; IL injection locking
layer to spin-polarize the charge current. With the recent emergence of the spin Hall
effect, a new type of spintronic oscillator, the SHNO, has been developed [172]. This
provides a new route for the development of microwave and magnonic devices [173].
SHNOs exhibit several advantages over STNOs, including easier nano-fabrication
[174–176], lower threshold current, direct optical access to the magnetodynamically
active area [177–179], smaller and voltage tunable radiation losses [180, 181], and
suppressed nonlinear damping process [173]. While the linewidth of single SHNOs
is of the same order as that of STNOs, and their output power is currently lower
than that of STNOs, they can be mutually synchronized in both long chains and
large two-dimensional arrays, such that record high signal quality factors of 170,000
can be achieved [182, 183]. SHNOs hence offer an opportunity to implement novel
nanoscale microwave sources and emitters for wireless communications, nonlinear
frequency modulation, and magnonics applications [184–186]. For further details of
SHNO developments, issues, challenges, and application, we refer the reader to a
recent review article [15].
11 Summary and Outlook
In summary, MTJ-based STNOs are detectors continue to hold promise for applications, due to their high microwave power output and higher frequency tunability. In