Ferromagnetism and Street punk: Difference between pages

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'''Ferromagnetism''' is a phenomenon by which a material can exhibit a spontaneous magnetization, and is one of the strongest forms of [[magnetism]]. It is responsible for most of the magnetic behavior encountered in everyday life and, along with [[ferrimagnetism]], is the basis for all permanent magnets (as well as the metals that are noticeably attracted to them).

==The Definition Of Streetpunk==

==Ferromagnetic materials==

<table border="1" cellspacing="0" cellpadding="2" align="right">

<tr><th>Material</th><th>Curie<br> temp. (K)</th></tr>

<tr><td>[[Cobalt|Co]]</td><td>1388</td></tr>

<tr><td>[[Iron|Fe]]</td><td>1043</td></tr>

<tr><td>[[Magnetite|FeOFe₂O₃]]</td><td>858</td></tr>

<tr><td>NiOFe₂O₃</td><td>858</td></tr>

<tr><td>[[Copper|Cu]]OFe₂O₃</td><td>728</td></tr>

<tr><td>[[Magnesium|Mg]]OFe₂O₃</td><td>713</td></tr>

<tr><td>Mn[[Bismuth|Bi]]</td><td>630</td></tr>

<tr><td>[[Nickel|Ni]]</td><td>627</td></tr>

<tr><td>Mn[[Antimony|Sb]]</td><td>587</td></tr>

<tr><td>MnOFe₂O₃</td><td>573</td></tr>

<tr><td>[[Yttrium|Y]]₃Fe₅O₁₂</td><td>560</td></tr>

<tr><td>[[Chromium|Cr]][[Oxide|O]]₂</td><td>386</td></tr>

<tr><td>[[Manganese|Mn]][[Arsenic|As]]</td><td>318</td></tr>

<tr><td>[[Gadolinium|Gd]]</td><td>292</td></tr>

<tr><td>[[Dysprosium|Dy]]</td><td>88</td></tr>

<tr><td>[[Europium|Eu]]O</td><td>69</td></tr>

'''Street punk''' (also known as '''gutterpunk''' in several parts of the world) is both a subgenre of [[punk rock]] and a word that describes people, mostly young, who live on the streets. In the latter case, such people may not identify themselves as "punk."

<!-- The numbers in this table currently come from Kittel, as referenced in the text. Please don't add new numbers without adding the corresponding reference. -->

People described as "street punks" are mostly [[white]] (or [[Caucasian Race|Caucasian]]) working class, and/or inner city youth who usually have a punk-like appearance. This includes studded leather jackets customised by that individual, torn jeans, plaid [[BDSM fashion|bondage trousers]], bullet belts, studded belts, [[mohawk hairstyle]]s and dyed hair, [[body piercing|piercings]], et cetera. However, many don't have any such appearance, and are sometimes described as "Casuals". The word "punk," in this usage, may have a derogatory intent.

<caption align=bottom><small>A selection of crystalline ferromagnetic materials, along with their Curie temperatures in [[kelvin]]s (K). (Kittel, p. 449.)</small></caption>

</table>

== Streetpunk as a Subculture ==

There are a number of crystalline materials that exhibit ferromagnetism. The table, at right, lists a representative selection of them here, along with their [[Curie temperature]]s, the temperature above which they cease to be ferromagnetic (see below).

Streetpunk is also seen as a reaction against middle class art-school type punks like [[Generation X (band)|Generation X]], as well as what some view as mainstream "trendy" people who embrace the punk lifestyle in what is viewed as a superficial way. Some streetpunks, like some skinheads, even operated in [[crew]]s; these crews sometimes have unifying political agendas and beliefs that kept them together. Others simply exist as house-sized inner-city communes who help each other survive. Although this only occurs amongst the most poverty-stricken of the punk rock subculture and has become uncommon in the [[21st century]], it is worth noting. Also, those "streetpunks" who engage in tribalism are less likely ever to "grow out" of the subculture. More often than not [[Marxist]]s and anarchists hold to the streetpunk music genre due to its subject matter, described below.

Ferromagnetic metal alloys whose constituents are not themselves ferromagnetic in their pure forms are called [[Heusler alloy]]s, named after [[Fritz Heusler]] (1903).

== Streetpunk Music ==

One can also make amorphous (non-crystalline) ferromagnetic metallic alloys by very rapid quenching (cooling) of a liquid alloy. These have the advantage that their properties are nearly isotropic (not aligned along a crystal axis); this results in low coercivity, low [[hysteresis]] loss, high permeability, and high electrical resistivity. A typical such material is a transition metal-metalloid alloy, made from about 80% transition metal (usually Fe, Co, or Ni) and a metalloid component ([[Boron|B]], [[Carbon|C]], [[Silicon|Si]], [[Phosphorus|P]], or [[Aluminium|Al]]) that lowers the melting point.

The street punk music genre started with the [[Oi!]] music scene in the late [[1970s]] and early [[1980s]] in [[Great Britain]], but on early streetpunk acts one can still feel the influence of late 70s British pub rock and cockney glam noize. This form of music was developed by bands such as [[Cock Sparrer]], [[The Business]], [[4-Skins]] and [[The Cockney Rejects]]. It started as a youth music style with songs about tales of the street, [[crew]] or [[gang]] life, police violence, easy girls, and teenage drunk mayhem. Streetpunk bands of the mid '80s include [[The Skeptix]], [[Abrasive Wheels]], and [[Attak]]. Today street punk bands can be found all over the world. Today's street punk is dominated by [[the Casualties]], [[Deadline]], [http://wastekrew.cjb.net USA Waste][[A Global Threat]], [[Career Soldiers]], [[The Unseen]], [[Cheap Sex]], [[Lower Class Brats]], and others. Their lyrics often talk about having fun at shows, unity, police oppression, social problems, anti-establishment and the punk scene itself.

One example of such an amorphous alloy is Fe₈₀B₂₀ (Metglas 2605) which has a Curie temperature of 647 K and a room-temperature (300 K) saturation magnetization of 125.7 [[tesla (unit)|milliteslas]] (1257 [[gauss]]), compared with 1043 K and 170.7 mT (1707 gauss) for pure iron from above. The melting point, or more precisely the glass transition temperature, is only 714 K for the alloy versus 1811 K for pure iron.

==Physical=Streetpunk originBands===

The following list of musicians and bands are identified with the streetpunk subculture, but not all of them are considered to be of the [[Oi!]] or streetpunk genre of music.

The property of ferromagnetism is due to the direct influence of two effects from [[quantum mechanics]]: [[spin (physics)|spin]] and the [[Pauli exclusion principle]].

*[[4-Skins]]

The spin of an [[electron]], combined with its [[planetary orbit|orbital]] [[angular momentum]], results in a magnetic [[dipole]] [[Magnetic_moment|moment]] and creates a [[magnetic field]]. (The classical analogue of quantum-mechanical spin is a spinning ball of charge, but the quantum version has distinct differences, such as the fact that it has discrete up/down states that are not described by a [[vector (spatial)|vector]]; similarly for "orbital" motion, whose classical analogue is a [[current (electricity)|current]] loop.) In many materials (specifically, those with a filled [[electron shell]]), however, the total dipole moment of all the electrons is zero (e.g. the spins are in up/down pairs). Only atoms with partially filled shells (e.g. unpaired spins) can experience a net magnetic moment in the absence of an external field. A ferromagnetic material has many such electrons, and if they are aligned they create a measurable macroscopic field.

*[[A Global Threat]]

*[[Abrasive Wheels]]

*[[Against All Authority]]

*[[Ann Beretta]]

*[[Anti-Heroes]]

*[[Attak]]

*[[The Brassknuckle Boys]]

*[[The Briggs]]

*[[The Bruisers]]

*[[The Business]]

*[[Career Soldiers]]

*[[The Casualties]]

*[[Cheap Sex]]

*[[Cock Sparrer]]

*[[The Cockney Rejects]]

*[[Clit 45]]

*[[Damage Case]]

*[[Deadline]]

*[[Dissucks]]

*[[The Forgotten]]

*[[The God Awfuls]]

*[[I Farm]]

*[[Kill The Man Who Questions]]

*[[Lifetime (band) | Lifetime]]

*[[Lower Class Brats]]

*[[Oxymoron]]

*[[Pistol Grip]]

*[[Rizzo Machine]]

*[[The Skabs]]

*[[The Skeptix]]

*[[Swingin' Utters]]

*[[The Templars]]

*[[Time bomb 77]]

*[[The Unseen]]

*[[The Varukers]]

*[[Le Fray]]

*[[Circle Jerks]]

[[Category:Punk genres]]

These permanent dipoles (often called simply "spins" even though they also generally include orbital angular momentum) tend to align in parallel to an external magnetic field, an effect called [[paramagnetism]]. (A related but much smaller effect is [[diamagnetism]], due to the orbital motion ''induced'' by an external field, resulting in a dipole moment ''opposite'' to the applied field.) Ferromagnetism involves an additional phenomenon, however: the dipoles tend to ''align spontaneously'', without any applied field. This is a purely quantum-mechanical effect.

[[de:Streetpunk]]

According to classical [[electromagnetism]], two nearby magnetic dipoles will tend to align in ''opposite'' directions (which would create an [[antiferromagnetism|antiferromagnetic]] material). In a ferromagnet, however, they tend to align in the ''same'' direction because of the Pauli principle: two electrons with the same spin state cannot lie at the same position, and thus feel an effective additional repulsion that lowers their electrostatic energy. This difference in energy is called the ''exchange energy'' and induces nearby electrons to align.

At long distances (after many thousands of ions), the exchange energy advantage is overtaken by the classical tendency of dipoles to anti-align. This is why, in an equilibriated (non-magnetized) ferromagnetic material, the dipoles in the whole material are not aligned. Rather, they organize into '''magnetic domains''' that are aligned (magnetized) at short range, but at long range adjacent domains are anti-aligned. The transition between two domains, where the magnetization flips, is called a [[Domain wall]] (e.g. a [[Bloch wall|Bloch]]/[[N&eacute;el wall]], depending upon whether the magnetization rotates parallel/perpendicular to the ___domain interface) and is a gradual transition on the atomic scale (covering a distance of about 300 ions for iron).

Thus, an ordinary piece of iron generally has little or no net magnetic moment. However, if it is placed in a strong enough external magnetic field, the domains will re-orient in parallel with that field, and will remain re-oriented when the field is turned off, thus creating a "permanent" magnet. This magnetization as a function of the external field is described by a [[hysteresis]] curve. Although this state of aligned domains is not a minimal-energy configuration, it is extremely stable and has been observed to persist for millions of years in seafloor [[magnetite]] aligned by the Earth's magnetic field (whose [[North Pole#Magnetic North|poles]] can thereby be seen to flip at long intervals). The net magnetization can be destroyed by heating and then cooling (''annealing'') the material without an external field, however.

As the temperature increases, thermal oscillation, or entropy, competes with the ferromagnetic tendency for dipoles to align. When the temperature rises beyond a certain point, called the '''Curie temperature''', there is a second-order [[phase transition]] and the system can no longer maintain a spontaneous magnetization, although it still responds paramagnetically to an external field. Below that temperature, there is a spontaneous symmetry breaking and random domains form (in the absence of an external field). The Curie temperature itself is a [[critical point]], where the [[magnetic susceptibility]] is theoretically infinite and, although there is no net magnetization, ___domain-like spin correlations fluctuate at all lengthscales.

The study of ferromagnetic phase transitions, especially via the simplified [[Ising model|Ising]] spin model, had an important impact on the development of statistical physics. There, it was first clearly shown that [[mean field theory]] approaches failed to predict the correct behavior at the critical point (which was found to fall under a ''universality class'' that includes many other systems, such as liquid-gas transitions), and had to be replaced by [[renormalization group]] theory.

==Unusual ferromagnetism==

In 2004, it was reported that a certain [[allotropy|allotrope]] of [[carbon]], [[nanofoam]], exhibited ferromagnetism. The effect dissipates after a few hours at room temperature, but lasts longer at cold temperatures. The material is also a [[semiconductor]]. It is thought that other similarly formed materials, of boron and nitrogen, may also be ferromagnetic.

==See also==

* [[antiferromagnetism]]

* [[diamagnetism]]

* [[ferrimagnetism]]

* [[ferromagnetic interaction]]

* [[paramagnetism]]

==References==

* Charles Kittel, ''Introduction to Solid State Physics'' (Wiley: New York, 1996).

* Neil W. Ashcroft and N. David Mermin, ''Solid State Physics'' (Harcourt: Orlando, 1976).

* John David Jackson, ''Classical Electrodynamics'' (Wiley: New York, 1999).

* E. P. Wohlfarth, ed., ''Ferromagnetic Materials'' (North-Holland, 1980).

* "Nanofoam makes magnetic debut," ''Physics World'' '''17''' (5), 3 (May 2004).

* "Heusler alloy," ''Encyclopedia Britannica Online'', retrieved Jan. 23, 2005.

* F. Heusler, W. Stark, and E. Haupt, ''Verh. der Phys. Ges.'' '''5''', 219 (1903).

[[Category:Electric and magnetic fields in matter]]

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