Spin wave (= magnon quasiparticle ) is unreal, useless forever.

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Spintronics doesn't use spin

Spin wave is just a transient short-lived magnetic fluctuation irrelevant to unphysical spin.

(Fig.1)  No progress.  Despite extremely longtime researches wasting money, spin wave = quasiparticle magnon has been useless since 1930s

Despite extremely long years of researches (= 1930s~ ), overhyped spin wave is still useless, No hope of practical use.

Spin wave expressed as fictional magnon quasiparticle is just a very unstable, ultra-short-lived magnetic fluctuation (= caused by electron's orbits instead of unphysical spin ) in magnetic material excited by laser light or electric voltage.

Overhyped news often makes an unfounded claim that this spin wave is "promising" with "potential" (= the use of future words = "promising, potential, step closer" means still useless now) to realize energy-efficient spintronics device with low energy loss someday (= actually, spin wave is very energy-inefficient ).

Actually, despite extremely long years of fruitless researches (= since 1930s ) and the media-hype, this spin wave is still useless, with No practical application, which fact proves spin wave can never be put to practical use.

The 8th and 10th paragraphs of this hyped news (10/2024) say
"The performance can be limited under low levels of excitation, which can make it difficult for this method to be used for highly nonlinear information transformation."

"With this, researchers believe (= just believe, still unrealized ) practical implementation is near (= still impractical despite extremely long research since 1930s )."

Spin wave is extremely energy-inefficient, contrary to hypes.

Contrary to these overhyped claims, this spin wave is extremely energy-inefficient, and too easily loses energy.

This 2024 review of (still-useless) spin wave ↓

p.6-right-2nd-paragraph says "the technological development of truly quantum magnonic (= spin wave ) platforms is still in its infancy"

p.7-right-2nd-paragraph says "The electric-field-induced excitation and manipulation of SWs (= spin waves ) are in the infant stage and associated with many challenges"

p.13-right-2nd-paragraph says "The biggest challenge is to increase the energy efficiency of the amplification process (= amplifying spin wave is very energy-inefficient )"

p.17-left-current and future challenges say "most of these methods have drawbacks such as low excitation efficiency (= spin wave is energy-inefficient )"

Spin wave (= very weak magnetic fluctuation ) decays in only nanoseconds, which is completely useless for (hyped) data storage, memory device, magnon computer.

(Fig.2)  Very short-lived spin magnetic wave (= lifetime is only nanoseconds = ns ) can propagate only micrometers (= μm ), which is useless for any spintronics devices.

Spin wave decays in only nanoseconds (= ns ), propagates only micrometers (= μm ), which is too short-lived to be practical.

The lifetime of this impractical spin wave (= magnon ) is extremely short (= only nanoseconds,  this 2nd-paragraph,  this p.8-Fig.8,  this p.4-Fig.3d ).

This p.1-left says
"However, the utilisation of magnons (= spin wave ) in magnonic applications can be limited by their lifetime, which can range from a few tenths of a microsecond down to tens of femtoseconds"  ← magnon or spin wave is too short-lived to be practical

This abstract-middle says
"A long-range spin-wave propagation is observed with a decay length of up to (8.0 ± 1.5) μm and a large spin-wave lifetime of up to (44.7 ± 9.1) ns"  ← Spin wave is too short-lived (= only 44 ns lifetime ) to be a practical device such as memory.

This extremely short-lived spin wave can propagate only micrometers ( this-abstract,  this abstract ) ~ millimeters (= damping ), which are too unstable and too short-lived to be a practical memory or data transfer spintronics device ( this p.3-Table I ).

This p.1-left-1st-paragraph says
"One challenge in spin-wave based applications is the strong spin wave damping such that it can only propagate a relatively short distance, order of millimetres even for yttrium iron garnets"

This p.2-2nd-paragraph says "SW (= spin wave ) decay length of 50 μm"

Exciting or generating spin wave consumes a lot of energy, which is extremely energy-inefficient.  And manipulation and detection of spin wave is also too difficult to be practical.

This p.1-right-2nd-paragraph says "exciting and probing magnons efficiently in 2D ferromagnets remain a challenge"

This p.1-left-2nd-paragraph says
"However, these spin waves have either short decay lengths or are experimentally very difficult to excite and detect"

As a result, contrary to a lot of hypes (= "promising" spin wave or something ), spin wave or magnon has been deadend for a long time, with No hope of practical application.

(Fig.3)  Physicists just artificially fit parameters to experiments without quantum mechanical calculation nor prediction of fictional spin wave or magnon quasiparticle.

Spin wave is irrelevant to quantum mechanics or spin.

Quantum mechanics unable to describe atoms as real objects has to express this (fictitious) spin wave or magnon quasiparticle as nonphysical math symbols with No concrete shape ( this p.2,  this p.9-(55) ).

Furthermore, quantum mechanics cannot predict the behavior of this spin wave, so there is No theoretical evidence of electron spin.

In order to describe this spin wave, physicists have to rely on classical Landau-Lifshitz-Gilbert (= LLG ) equation ( this p.6(or p.3)-1st-paragraph ) with artificially-chosen parameters such as damping parameter α which must be fit to experiments ( this p.11,15,  this p.7-left,  this p.67(or p.60)-4th-paragraph ) without quantum mechanical prediction.

This p.4-2nd-last-paragraph says
"The damping parameter is generally set to suit the needs of the experiment. We have used an experimental value for bcc iron and fcc cobalt as a reference when choosing α"

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